Acesulfame Potassium Compositions and Processes for Producing Same

ABSTRACT

A process for producing acesulfame potassium, the process comprising the steps of providing a cyclizing agent composition comprising a cyclizing agent and a solvent and having an initial temperature, cooling the cyclizing agent composition to form a cooled cyclizing agent composition having a cooled temperature less than 35° C., reacting an acetoacetamide salt with the cyclizing agent in the cooled cyclizing agent composition to form a cyclic sulfur trioxide adduct composition comprising cyclic sulfur trioxide adduct; and, forming from the cyclic sulfur trioxide adduct in the cyclic sulfur trioxide adduct composition the finished acesulfame potassium composition comprising non-chlorinated acesulfame potassium and less than 39 wppm 5-chloro-acesulfame potassium. The cooled temperature is at least 2° C. less than the initial temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/397,528, filed Sep. 21, 2016, and to U.S. Provisional PatentApplication No. 62/397,520, filed Sep. 21, 2016, the entireties of whichare incorporated herein by reference.

FIELD OF INVENTION

The present invention relates generally to acesulfame potassium and toprocesses for producing acesulfame potassium. More specifically, thepresent invention relates to processes for producing high purityacesulfame potassium.

BACKGROUND OF THE INVENTION

Acesulfame potassium has an intense, sweet taste and has been used inmany food-related applications as a sweetener. In conventionalacesulfame potassium production processes, sulfamic acid and an amine,e.g., triethylamine, are reacted to form an amidosulfamic acid salt,such as a trialkyl ammonium amidosulfamic acid salt. The amidosulfamicacid salt is then reacted with diketene to form an acetoacetamide salt.The acetoacetamide salt may be cyclized, hydrolyzed, and neutralized toform acesulfame potassium. U.S. Pat. Nos. 5,744,010 and 9,024,016disclose exemplary acesulfame potassium production processes.

Typically, the acetoacetamide salt intermediate is cyclized by reactionwith sulfur trioxide in an inorganic or organic solvent to form a cyclicsulfur trioxide adduct. The solvent routinely utilized in this reactionis an organic solvent such as a halogenated, aliphatic hydrocarbonsolvent, for example, dichloromethane. The adduct formed by thisreaction is subsequently hydrolyzed and then neutralized with potassiumhydroxide to form acesulfame potassium.

Acesulfame potassium and the intermediate compositions produced byconventional methods contain undesirable impurities, such as5-chloro-acesulfame potassium. Limits for the content of variousimpurities are often set by governmental regulations or customerguidelines. Due to their similar chemical structures and properties,separation of 5-chloro-acesulfame potassium from the desirednon-chlorinated acesulfame potassium, using standard purificationprocedures such as crystallization has proven difficult, resulting inconsumer dissatisfaction and the failure to meet regulatory standards.

The need exists for an improved process for producing high purityacesulfame potassium compositions in which the formation of5-chloro-acesulfame potassium during synthesis is reduced or eliminated.

All of the references discussed herein are hereby incorporated byreference.

SUMMARY OF THE INVENTION

The application discloses processes for producing a finished acesulfamepotassium composition, the process comprising the steps of providing acyclizing agent composition comprising a cyclizing agent and a solventand having an initial temperature, cooling the cyclizing agentcomposition to form a cooled cyclizing agent composition having a cooledtemperature less than 35° C., reacting an acetoacetamide salt with thecyclizing agent in the cooled cyclizing agent composition to form acyclic sulfur trioxide adduct composition comprising cyclic sulfurtrioxide adduct; and forming from the cyclic sulfur trioxide adduct inthe cyclic sulfur trioxide adduct composition the finished acesulfamepotassium composition comprising non-chlorinated acesulfame potassiumand less than 39 wppm 5-chloro-acesulfame potassium, e.g., from 1 wppbto 5 wppm 5-chloro-acesulfame potassium. The cooled temperature is atleast 2° C. less than the initial temperature. The finished acesulfamepotassium composition may comprise at least 90% by weight of the5-chloro-acesulfame potassium present in the crude acesulfame potassiumcomposition. The forming of the finished acesulfame potassiumcomposition from the cyclic sulfur trioxide adduct may comprise thesteps of hydrolyzing the cyclic sulfur trioxide adduct in the cyclicsulfur trioxide adduct composition to form an acesulfame-H compositionand neutralizing the acesulfame-H in the acesulfame H composition toform a crude acesulfame potassium composition comprising non-chlorinatedacesulfame potassium and less than 39 wppm 5-chloro-acesulfamepotassium, and forming the finished acesulfame potassium compositionfrom the crude acesulfame potassium composition. The forming of thefinished acesulfame potassium composition may comprise the steps ofconcentrating the crude acesulfame composition to form an intermediateacesulfame potassium composition comprising at least 10 wt % acesulfamepotassium and separating the intermediate acesulfame potassiumcomposition to form the finished acesulfame potassium compositioncomprising at least 15 wt % acesulfame potassium. The provision of thecyclizing agent composition may comprise the step of contacting thesolvent and the cyclizing agent to form the cyclizing agent composition,and a contact time from the beginning of the contacting step to thebeginning of reacting step (c) may be less than 60 minutes. In somecase, the cooled cyclizing agent composition has a cooled temperatureless than 25° C., the crude acesulfame potassium composition comprisesfrom 1 wppb to 39 wppm 5-chloro-acesulfame potassium, and the finishedacesulfame potassium composition comprises from 1 wppb to 5 wppm5-chloro-acesulfame potassium. In some cases, the cooled cyclizing agentcomposition has a cooled temperature ranging from −35° C. to 15° C., thecrude acesulfame potassium composition comprises from 1 wppb to 5 wppm5-chloro-acesulfame potassium, and the finished acesulfame potassiumcomposition comprises from 1 wppb to 2.7 wppm 5-chloro-acesulfamepotassium. In some cases, the cooled cyclizing agent composition has acooled temperature less than 25° C., the contact time is less than 15minutes, the crude acesulfame potassium composition comprises from 1wppb to 39 wppm 5-chloro-acesulfame potassium, and the finishedacesulfame potassium composition comprises from 1 wppb to 5 wppm5-chloro-acesulfame potassium. In some cases, the cooled cyclizing agentcomposition has a cooled temperature ranging from −35° C. to 15° C., thecontact time is less than 5 minutes, the crude acesulfame potassiumcomposition comprises from 1 wppb to 39 wppm 5-chloro-acesulfamepotassium, and the finished acesulfame potassium composition comprisesfrom 1 wppb to 5 wppm 5-chloro-acesulfame potassium. In someembodiments, the cooled cyclizing agent composition comprises less than1 wt % cyclizing agent/solvent reaction product selected from the groupconsisting of chloromethyl chlorosulfate and methyl-bis-chlorosulfateand/or the weight ratio of solvent to cyclizing agent in the cyclizingagent composition is at least 1:1. In one embodiment, the processcomprises the steps of providing a solvent, cooling the solvent,combining the cooled solvent with a cyclizing agent to form a cooledcyclizing agent composition having a cooled temperature less than 35°C., reacting an acetoacetamide salt with the cyclizing agent in thecyclizing agent composition to form a cyclic sulfur trioxide adductcomposition, and forming from the cyclic sulfur trioxide adductcomposition the finished acesulfame potassium composition. In anotheraspect, the disclosure relates to a process for producing a finishedacesulfame potassium composition, the process comprising the steps ofproviding a cyclic sulfur trioxide adduct composition comprising one ormore of chloromethyl chlorosulfate and methyl-bis-chlorosulfate presentin a collective amount less than 1 wt %; and forming the finishedacesulfame potassium composition from the cyclic sulfur trioxide adductcomposition. The provision of the cyclic sulfur trioxide adductcomposition may comprise the steps of reacting sulfamic acid andtriethylamine to form an amidosulfamic acid salt, reacting theamidosulfamic acid salt and diketene to form acetoacetamide salt,providing a cyclizing agent composition comprising a sulfur trioxide anddichloromethane and having an initial temperature, cooling the cyclizingagent composition to form a cooled cyclizing agent composition having acooled temperature below 35° C., and reacting the acetoacetamide saltwith sulfur trioxide in the cooled cyclizing agent composition to formthe cyclic sulfur trioxide adduct composition. Preferably, the cooledtemperature is at least 2° C. less than the initial temperature. In somecases, the providing step comprises the step of contacting the solventand the cyclizing agent to form the cyclizing agent composition and acontact time from the beginning of the contacting step to the beginningof the reacting step is less than 15 minutes, and the cooled cyclizingagent composition has a cooled temperature less than 25° C., the crudeacesulfame potassium composition comprises from 1 wppb to 39 wppm5-chloro-acesulfame potassium, and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium. In some cases, the providing step comprises the step ofcontacting the solvent and the cyclizing agent to form the cyclizingagent composition and a contact time from the beginning of thecontacting step to the beginning of the reacting step is less than 5minutes, and the cooled cyclizing agent composition has a cooledtemperature ranging from −35° C. to 15° C., the crude acesulfamepotassium composition comprises from 1 wppb to 39 wppm5-chloro-acesulfame potassium, and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium. In one embodiment, the process comprises the steps ofreacting sulfamic acid and triethylamine to form an amidosulfamic acidsalt, reacting the amidosulfamic acid salt and diketene to formacetoacetamide salt, providing a cyclizing agent composition comprisinga sulfur trioxide and dichloromethane and having an initial temperature,cooling the cyclizing agent composition to form a cooled cyclizing agentcomposition having a cooled temperature less than 35° C., reacting theacetoacetamide salt with sulfur trioxide in the cooled cyclizing agentcomposition to form a cyclic sulfur trioxide adduct, hydrolyzing thecyclic sulfur trioxide adduct to form an acesulfame-H compositioncomprising acesulfame-H, neutralizing the acesulfame-H in theacesulfame-H to form a crude acesulfame potassium composition comprisingnon-chlorinated acesulfame potassium and from 1 wppb to 39 wppm5-chloro-acesulfame potassium acid, and treating the crude acesulfamepotassium composition to form the finished acesulfame potassiumcomposition comprising acesulfame potassium and less than 37 wppmacetoacetamide-N-sulfonic acid (the reacting, providing, and coolingsteps can be performed in any order before the reaction of theacetoacetamide salt with sulfur trioxide). The cooled temperature may beat least 2° C. less than the initial temperature, and the providing stepcomprises the step of contacting the solvent and the cyclizing agent toform the cyclizing agent composition. Contact time may be less than 60minutes. In some cases, contact time is less than 15 minutes, the cooledcyclizing agent composition has a cooled temperature less than 25° C.,the crude acesulfame potassium composition comprises from 1 wppb to 39wppm 5-chloro-acesulfame potassium, and the finished acesulfamepotassium composition comprises from 1 wppb to 5 wppm5-chloro-acesulfame potassium. In some cases, contact time is less than5 minutes, the cooled cyclizing agent composition has a cooledtemperature ranging from −35° C. to 15° C., the crude acesulfamepotassium composition comprises from 1 wppb to 39 wppm5-chloro-acesulfame potassium, and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium. The application also describes crude, intermediate, andfinished acesulfame potassium composition produced by the processesdescribed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail below with reference to theappended drawing.

FIG. 1 is a process flow sheet of an acesulfame potassium productionprocess in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Introduction

Conventional processes for producing acesulfame potassium involvereacting sulfamic acid and an amine in the presence of acetic acid toform an amidosulfamic acid salt. The amidosulfamic acid salt is thenreacted with an acetoacetylating agent, e.g., diketene, to form anacetoacetamide salt. The acetoacetamide salt is reacted with a cyclizingagent, e.g., sulfur trioxide, to form a cyclic sulfur trioxide adduct.The cyclic sulfur trioxide adduct is then hydrolyzed and neutralized viaconventional means to form a crude acesulfame potassium compositioncomprising acesulfame potassium. This composition is phase separatedinto aqueous and organic phases. Most of the acesulfame potassiumseparates into the aqueous phase. As used herein, the term “crudeacesulfame potassium composition” refers to the initial product of a theneutralization reaction or to the aqueous phase that is formed from thephase separation step (without any further purification). The crudeacesulfame potassium composition comprises at least 5 wt % acesulfamepotassium. The crude acesulfame potassium composition may be optionallytreated to form an “intermediate acesulfame potassium composition”and/or a “finished acesulfame potassium composition,” which arediscussed below.

Conventional acesulfame potassium compositions have been shown tocomprise several undesirable impurities, among them 5-chloro-acesulfamepotassium and acetoacetamide. Content limits for these compounds in thefinished acesulfame potassium composition are often determined byindustry purity standards and/or by standards established for theparticular end use products that utilize acesulfame potassium as asweetener. In some cases, limits for these impurities are determined bygovernmental regulations. For most applications, high acesulfamepotassium purity levels are preferred. Because the chemical structure of5-chloro-acesulfame potassium is similar to that of non-chlorinatedacesulfame potassium, separation of 5-chloro-acesulfame potassium usingstandard purification procedures such as crystallization has provendifficult.

Without being bound by theory, it has now been discovered that thereaction of the cyclizing agent with the acetoacetamide salt to form thecyclic sulfur trioxide adduct may also involve side reactions that formthe 5-chloro-acesulfame potassium impurity.

The use of specific reaction parameters, however, may advantageouslyreduce or eliminate 5-chloro-acesulfame potassium formation or theformation of its precursor, 5-chloro-acesulfame-H. In particular, it hasnow been discovered that utilizing a low temperature cyclizing agentcomposition and/or cooling the cyclizing agent composition, e.g., to atemperature less than 35° C., surprisingly reduces or eliminates5-chloro-acesulfame potassium formation in the crude, intermediate, andfinished acesulfame potassium compositions. In addition, the reducedimpurity levels in these acesulfame potassium compositions reduce oreliminate the need for additional purification steps, resulting inoverall improved process efficiency.

It is postulated that the reaction of the cyclizing agent, the solvent,and optionally other components may lead to the formation ofchlorine/chloride-containing compounds. Exemplary cyclizingagent/solvent reaction products include halogen-containing compoundssuch as chlorine/chloride-containing compounds, e.g., chlorosulfates.These compounds, in turn, may react to chlorinate the acesulfameprecursor acid, acesulfame-H, sometimes referred to as sweetener acid,or its precursors, e.g., acetoacetamide-N-sulfonate. By cooling thecyclizing agent composition (before the cyclization reaction) andoptionally by limiting contact time, lower amounts ofchlorine/chloride-containing compounds (e.g., chlorosulfates) are formed(as compared to the amount formed when higher temperatures, andoptionally greater contact times, are employed). That is, lowertemperatures and optionally shorter contact times have now been shown toretard the formation of chlorine/chloride-containing compounds, e.g.,chlorosulfates. As a result of the lower temperatures, and optionallyshorter contact times, in one embodiment, the cyclizing agentcomposition may have a low chlorine/chloride-containing compoundcontent, e.g., a low chlorosulfate content, as discussed herein. Thereduction or elimination of chlorine/chloride-containing compoundsdirectly leads to the formation of high purity acesulfame potassiumcompositions. Without being bound by theory, it is postulated thatwithout limiting temperature (and optionally contact time) as describedherein, resultant crude, intermediate, and finished acesulfame potassiumcompositions will detrimentally have greater amounts of5-chloro-acesulfame potassium.

Additional specific terms that are used herein are now defined. “Contacttime,” as used herein, refers to the time period that the solventcontacts the cyclizing agent before formation of the cyclic sulfurtrioxide adduct. Thus, contact time begins when at least some of thesolvent contacts at least some the cyclizing agent to form the cyclizingagent/solvent mixture (“cyclizing agent composition”), and contact timeends when the acetoacetamide salt first contacts the cyclizing agent inthe cyclizing agent composition.

“Cyclization reaction time,” as used herein, refers to the time from thestart of the acetoacetamide salt feed to the termination of theacetoacetamide salt feed. In some cases, if indicated, the cyclizationreaction time may include additional time past the termination of theacetoacetamide salt feed, e.g., an extra 5 minutes or an extra minute.

“5-chloro-acesulfame potassium,” as used herein, refers to the followingmolecule:

“Acetoacetamide,” as used herein, refers to the following molecule:

“Acetoacetamide-N-sulfonic acid” as used herein, refers to the moleculeshown below. In some cases, acetoacetamide-N-sulfonic acid may be adegradation product of acesulfame potassium or acesulfame-H. The term“acetoacetamide-N-sulfonic acid,” as used herein, also includes salts ofacetoacetamide-N-sulfamic acid, e.g., potassium, sodium, and otheralkali metal salts.

An “intermediate acesulfame potassium composition” refers to acomposition resulting from the concentrating of the crude acesulfamepotassium composition, e.g., the removal of water from the crudeacesulfame potassium composition. The intermediate acesulfame potassiumcomposition comprises at least 10 wt % acesulfame potassium, based onthe total weight of the intermediate acesulfame potassium composition,and has an acesulfame potassium weight percentage that is higher thanthat of the crude acesulfame potassium composition.

A “finished acesulfame potassium composition” refers to a composition(preferably directly) resulting from the separating, e.g., crystallizingand/or filtering, of the intermediate acesulfame potassium composition.The finished acesulfame potassium composition comprises at least 15 wt %acesulfame potassium, based on the total weight percentage of thefinished acesulfame potassium composition, and has an acesulfamepotassium weight percentage that is higher than that of the intermediateacesulfame potassium composition.

“Wppm” and “wppb,” as used herein, mean weight parts per million orweight parts per billion, respectively. These are based on the totalweight of the respective composition, e.g., the total weight of theentire crude acesulfame potassium composition or the entire finishedacesulfame potassium composition.

Acesulfame Potassium Formation (Cooled Cyclizing Agent Composition)

Processes for producing acesulfame potassium exhibiting high levels ofpurity is described herein.

In one embodiment, the process comprises the step of providing acyclizing agent composition comprising a cyclizing agent and optionallya solvent (the formation of the cyclizing agent composition is discussedin more detail below). The cyclizing agent composition has an initialtemperature, which typically will be an elevated temperature, e.g.,greater than 35° C. The process further comprises the step of coolingthe cyclizing agent composition to form a cooled cyclizing agentcomposition that has a cooled temperature. The cooled temperature ispreferably at least 2° C. less than the initial temperature. In someembodiments the cooled temperature is less than 35° C.

Importantly, the cooled cyclizing agent composition is provided at a lowtemperature, e.g., lower than the initial temperature of the cyclizingagent composition. In one embodiment, the process further comprises thesteps of reacting an acetoacetamide salt with the cyclizing agent in thecooled cyclizing agent composition to form a cyclic sulfur trioxideadduct composition. The process also comprises forming a finishedacesulfame potassium composition from the cyclic sulfur trioxide adductcomposition. As noted above, the cyclic sulfur trioxide adductcomposition may be hydrolyzed and neutralized to yield a crudeacesulfame potassium composition. Also, the crude acesulfame potassiumcomposition may be treated, e.g., concentrated and separated to form thefinished acesulfame potassium composition.

The reaction of the acetoacetamide salt and the cyclizing agent isconducted by contacting the two reactants, which are preferably fed,either separately or simultaneously (co-fed), to a reaction vessel. Forexample, the acetoacetamide salt may be added to the cyclizing agentcomposition, e.g., added drop-wise to the cyclizing agent composition.Alternatively, the cyclizing agent composition may be added to theacetoacetamide salt, e.g., added drop-wise to the acetoacetamide salt.

In some embodiments, the cooled cyclizing agent composition has atemperature less than 35° C., e.g., less than 32° C., less than 30° C.,less than 25° C., less than 20° C., less than 15° C., less than 12° C.,less than 11° C., less than 10° C., less than 8° C., less than 5° C.,less than 3° C., less than 1° C., or less than 0° C. In terms of ranges,the cooled cyclization agent composition has a temperature ranging from−45° C. to 35° C., e.g., −45° C. to 25° C., −40° C. to 15° C., −35° C.to 15° C.,−35° C. to 10° C., −30° C. to 25° C., −30° C. to 10° C., −15°C. to 25° C., from −15° C. to 15° C., from −10° C. to 12° C., from −8°C. to 10° C., or −8° C. to 5° C.

The initial temperature of the cyclizing agent composition may varywidely, as long as it is greater than the cooled temperature of thecooled cyclizing agent composition. In some embodiments, the coolingstep reduces the temperature of the cyclizing agent composition (asinitially provided), e.g., by at least 2° C., at least 3° C., at least5° C., at least 10° C., at least 15° C., at least 20° C., or at least25° C. In terms of ranges, the cooling step reduces the temperature ofthe cyclizing agent composition by from 2° C. to 70° C., e.g., from 3°C. to 65° C., from 5° C. to 50° C., from 5° C. to 35° C., or from 10° C.to 30° C.

In some embodiments, initial temperature of the cyclizing agentcomposition is less than 50° C., e.g., less than 40° C., less than 35°C., less than 25° C., less than 20° C., less than 15° C., less than 12°C., less than 11° C., or less than 10° C. In terms of ranges, theinitial temperature of the cyclizing agent composition ranges from −45°C. to 50° C., e.g., −45° C. to 40° C., −40° C. to 35° C.,−35° C. to 15°C., −35° C. to 10° C., −30° C. to 25° C., −30° C. to 10° C., −15° C. to25° C., from −15° C. to 15° C., from −10° C. to 12° C., from −8° C. to10° C., or −8° C. to 5° C. In terms of lower limits, the initialtemperature of the cyclizing agent composition may be at least −45° C.,e.g., at least −35° C., at least −25° C., at least −15° C., at least 0°C., or at least 5° C.

In one embodiment, the process employs the aforementioned providing (orcontacting), reacting, and forming steps. As a result of using thesespecific steps and parameters, the crude acesulfame potassiumcomposition comprises from 0.001 wppm to 39 wppm 5-chloro-acesulfamepotassium and the finished acesulfame potassium composition comprisesfrom 0.001 wppm to 5 wppm 5-chloro-acesulfame potassium.

The cooling of the low temperature cyclizing agent composition or theprovision of the low temperature cyclizing agent composition may beachieved through any of a variety of different cooling techniques. Forexample, the cooling step may be achieved by using one or more heatexchangers, refrigeration units, air cooling units, water cooling units,or a cooling medium, such as liquid nitrogen or other cryogenics. Ifheat exchangers are employed, a water/glycol mixture is a preferredexchange medium, with brine being a suitable alternative.

Cyclizing agent/solvent reaction products, e.g., chlorosulfates,undesireably may be formed when a cyclizing agent reacts with achlorine-containing solvent in the cyclyizing agent composition.Exemplary chlorosulfates include chloromethyl chlorosulfate andmethyl-bis-chlorosulfate.

It has now been discovered that by controlling the temperature of thecyclizing agent composition as discussed herein, fewer cyclizingagent/solvent reaction products, e.g., chlorosulfates, are formed. Thecooled cyclizing agent composition, for example, may have a lowcyclizing agent/solvent reaction product content, e.g., a lowchlorosulfate content. For example, the cyclizing agent composition maycomprise less than 1 wt % cyclizing agent/solvent reaction product,e.g., less than 0.75 wt %, less than 0.5 wt %, less than 0.25 wt %, lessthan 0.1 wt %, less than 0.05 wt %, or less than 0.01 wt %. In terms ofranges, the cyclizing agent composition may comprise from 1 wppm to 1 wt% cyclizing agent/solvent reaction products, e.g., from 10 wppm to 1 wt%, from 10 wppm to 0.75 wt %, from 10 wppm to 0.5 wt %, from 10 wppm to0.25 wt %, from 100 wppm to 0.75 wt %, from 100 wppm to 0.5 wt %, orfrom 100 wppm to 0.25 wt %. These ranges and limits apply to cyclizingagent/solvent reaction products generally and to specific reactionproducts generally, e.g., chloromethyl chlorosulfate,methyl-bis-chlorosulfate, and combinations thereof.

In one embodiment, the cooled cyclizing agent composition comprises oneor more of chloromethyl chlorosulfate and methyl-bis-chlorosulfate in acollective amount less than 1 wt %, e.g., less than 0.75 wt %, less than0.5 wt %, less than 0.25 wt %, less than 0.1 wt %, less than 0.05 wt %,or less than 0.01 wt %. In one embodiment, the cyclizing agentcomposition comprises less than 1 wt % chloromethyl chlorosulfate, e.g.,less than 0.75 wt %, less than 0.5 wt %, less than 0.25 wt %, less than0.1 wt %, less than 0.05 wt %, or less than 0.01 wt %. In anotherembodiment, the cyclizing agent composition comprises less than 1 wt %methyl-bis-chlorosulfate, e.g., less than 0.75 wt %, less than 0.5 wt %,less than 0.25 wt %, less than 0.1 wt %, less than 0.05 wt %, or lessthan 0.01 wt %. In another embodiment, the cyclizing agent compositioncomprises both chloromethyl chlorosulfate and methyl-bis-chlorosulfate,collectively, in an amount less than 1 wt %, e.g., less than 0.75 wt %,less than 0.5 wt %, less than 0.25 wt %, less than 0.1 wt %, less than0.05 wt %, or less than 0.01 wt %.

In some cases, the process comprises the steps of forming or providing acyclic sulfur trioxide adduct composition comprising less than 1 wt %cyclizing agent/solvent reaction product, e.g., chloromethylchlorosulfate and/or methyl-bis-chlorosulfate, and forming the finishedacesulfame potassium composition from the cyclic sulfur trioxide adductcomposition. The forming or providing of the cyclic sulfur trioxideadduct composition may vary widely as long as the cyclic sulfur trioxideadduct composition has the required cyclizing agent/solvent reactionproduct, e.g., chlorosulfate, content. Some methods of achieving thecyclic sulfur trioxide adduct composition include utilizing a cooledcyclizing agent composition in the reaction of the acetoacetamide saltwith the cyclizing agent, as discussed herein. This method of achievingthe cyclic sulfur trioxide adduct composition is merely exemplary and isnot meant to limit the scope of the process, and other suitable methodsare contemplated.

Thus, the use of a cooled cyclizing agent composition may result in theformation of a cyclic sulfur trioxide adduct composition having a lowcyclizing agent/solvent reaction product content, e.g., a lowchlorosulfate content. For example, the cyclic sulfur trioxide adductcomposition may comprise less than 1 wt % cyclizing agent/solventreaction product, e.g., less than 0.75 wt %, less than 0.5 wt %, lessthan 0.25 wt %, less than 0.1 wt %, less than 0.05 wt %, or less than0.01 wt %. In terms of ranges, the cyclic sulfur trioxide adductcomposition may comprise from 1 wppm to 1 wt % cyclizing agent/solventreaction products, e.g., from 10 wppm to 1 wt %, from 10 wppm to 0.75 wt%, from 10 wppm to 0.5 wt %, from 10 wppm to 0.25 wt %, from 100 wppm to0.75 wt %, from 100 wppm to 0.5 wt %, or from 100 wppm to 0.25 wt %.

In one embodiment, the cyclic sulfur trioxide adduct compositioncomprises one or more of chloromethyl chlorosulfate andmethyl-bis-chlorosulfate in a collective amount less than 1 wt %, e.g.,less than 0.75 wt %, less than 0.5 wt %, less than 0.25 wt %, less than0.1 wt %, less than 0.05 wt %, or less than 0.01 wt %. In oneembodiment, the cyclic sulfur trioxide adduct composition comprises lessthan 1 wt % chloromethyl chlorosulfate, e.g., less than 0.75 wt %, lessthan 0.5 wt %, less than 0.25 wt %, less than 0.1 wt %, less than 0.05wt %, or less than 0.01 wt %. In another embodiment, the cyclic sulfurtrioxide adduct composition comprises less than 1 wt %methyl-bis-chlorosulfate, e.g., less than 0.75 wt %, less than 0.5 wt %,less than 0.25 wt %, less than 0.1 wt %, less than 0.05 wt %, or lessthan 0.01 wt %. In another embodiment, the cyclic sulfur trioxide adductcomposition comprises both chloromethyl chlorosulfate andmethyl-bis-chlorosulfate, collectively, in an amount less than 1 wt %,e.g., less than 0.75 wt %, less than 0.5 wt %, less than 0.25 wt %, lessthan 0.1 wt %, less than 0.05 wt %, or less than 0.01 wt %.

In one embodiment, only the cyclizing agent (e.g., without solvent) iscooled, and then the cooled cyclizing agent is mixed with the solvent toform the cyclizing agent composition, which is then reacted with theacetoacetamide salt. That is, in some cases, the solvent (if present)may not be cooled in the same manner as the cyclizing agent is cooled.In other embodiments, only the solvent (without cyclizing agent) iscooled, and then the cooled solvent is mixed with the cyclizing agent toform the cyclizing agent composition. In some aspects both the solventand the cyclizing agent are cooled prior to being mixed together to formthe cyclizing agetn composition. Regardless of whether either or boththe solvent and the cyclizing agent are cooled prior to mixing, theresulting cyclizing agent composition optionally is further cooled.

Thus, in some cases, the cooling is implemented via multiple coolingsteps. For example, the solvent may be cooled to a first temperature,then combined with the cyclizing agent to form the cyclizing agentcomposition, which is then further cooled to a second temperature, whichis less than the first temperature. Conversely, in other aspects, thecyclizing agent is cooled to a first temperature, then combined with thesolvent to form the cyclizing agent composition, which is then furthercooled to a second temperature, which is less than the firsttemperature. In other embodiments, the cyclizing agent is cooled to afirst temperature, the solvent is cooled to a second temperature, andthe cooled cyclizing agent and the cooled solvent are combined andoptionally cooled to a third temperature, which is less than the firstand second temperatures. These cooling schemes are merely exemplary andare not intended to limit the scope of the cooling step.

In one embodiment, the solvent and cyclizing agent are combined in afirst vessel, e.g., a first reactor, to form a cyclizing agentcomposition, which is optionally cooled. The cyclizing agent compositionmay then be added to the acetoacetamide salt in a second reactor. In oneembodiment, the first vessel is chilled, e.g., to temperature below 35°C., prior to combining the solvent and cyclizing agent. In some aspects,the cyclizing agent and the solvent are cooled individually and then fedto the reaction with the acetoacetamide salt, optionally followed byadditional cooling.

In addition to the aforementioned cooling steps, it has also beendiscovered that, in cases where the cyclizing agent and solvent arecombined prior to reaction with the acetoacetamide salt, the formationof 5-chloro-acesulfame potassium may be advantageously further reducedor eliminated by reducing the contact time of the cyclizing agent andsolvent. Thus, reducing the contact time optionally may be combined withany of the above-described cooling steps. The inventors have found thatby limiting the contact time, less cyclizing agent/solvent reactionproducts, e.g., chlorosulfates such as chloromethyl chi orosulfate andmethyl-bis-chlorosulfate, are beneficially formed. As a result,reductions in the formation of 5-chloro-acesulfame potassium may beachieved in the crude, intermediate, and finished acesulfame potassiumcompositions.

In some embodiments, for example, contact time may be less than 60minutes, e.g., less than 45 minutes, less than 30 minutes, less than 15minutes, less than 10 minutes, less than 8 minutes, less than 5 minutes,less than 3 minutes, or less than 1 minute. In one embodiment, thesolvent and cyclizing agent are mixed and immediately reacted with theacetoacetamide salt. In terms of ranges, contact time may range from 1second to 60 minutes, e.g., from 10 seconds to 45 minutes, from 10seconds to 30 minutes, from 30 seconds to 30 minutes, from 1 minute to10 minutes, from 3 minutes to 10 minutes, or from 5 minutes to 10minutes. In preferred embodiments, as shown in the Examples, thecombination of short contact times and low temperatures surprisinglyleads to low 5-chloro-acesulfame potassium content in the crude,intermediate, and finished acesulfame potassium compositions.

The inventors have also found that if cyclization reaction time isminimized, the formation of impurities, e.g., organic impurities such as5-chloro-acesulfame potassium, is reduced or eliminated. In someembodiments, the cyclization reaction is conducted for a cyclizationreaction time less than 35 minutes, e.g., less than 30 minutes, lessthan 25 minutes, less than 20 minutes, less than 15 minutes, or lessthan 10 minutes. In terms of ranges, the cyclization reaction may beconducted for a cyclization reaction time ranging from 1 second to 35minutes, e.g., from 10 seconds to 25 minutes, from 30 seconds to 15minutes, or from 1 minute to 10 minutes.

Crude acesulfame compositions may be treated to form intermediateacesulfame potassium compositions and (subsequently) finished acesulfamepotassium compositions. The treatment operation may include one or moreconcentrating and/or separating operations.

For example, the treatment operation may comprise concentrating thecrude acesulfame potassium composition to form a water stream and anintermediate acesulfame potassium composition and then separating theintermediate acesulfame potassium composition to form the finishedacesulfame potassium composition comprising acesulfame potassium, e.g.,via filtration and/or crystallization.

Acesulfame Potassium Compositions

The crude acesulfame potassium composition is formed by hydrolyzing thecyclic sulfur trioxide adduct to form an acesulfame-H composition andneutralizing the acesulfame-H in the acesulfame-H composition to formthe crude acesulfame potassium composition, as discussed herein. Theproduct of the neutralization reaction may be phase separated intoaqueous and organic phases, and the crude acesulfame potassiumcomposition may be obtained from the aqueous phase (without any furtherpurification). The crude acesulfame potassium composition preferablycomprises non-chlorinated acesulfame potassium, and less than 39 wppm5-chloro-acesulfame potassium, e.g., less than 35 wppm, less than 34wppm, less than 33 wppm, less than 32 wppm, less than 31 wppm, less than30 wppm, less than 25 wppm, less than 24 wppm, less than 20 wppm, lessthan 15 wppm, less than 12 wppm, less than 10 wppm, less than 7 wppm,less than 5 wppm, less than 3 wppm, or less than 1 wppm. In some casesthe crude acesulfame potassium composition is free of5-chloro-acesulfame potassium, e.g., substantially free of5-chloro-acesulfame potassium (undetectable). In terms of ranges, thecrude acesulfame potassium composition may comprise from 1 wppb to 39wppm 5-chloro-acesulfame potassium, e.g., from 1 wppb to 35 wppm, from 1wppb to 34 wppm, from 1 wppb to 33 wppm, from 1 wppb to 32 wppm, from 1wppb to 31 wppm, from 1 wppb to 30 wppm, from 50 wppb to 34 wppm, from0.1 wppm to 34 wppm, from 0.1 wppb to 34 wppm, from 0.1 wppb to 33 wppm,from 1 wppb to 25 wppm, from 1 wppb to 20 wppm, from 1 wppb to 10 wppm,from 1 wppb to 5 wppm, from 1 wppb to 2.7 wppm, from 10 wppb to 20 wppm,from 10 wppb to 19 wppm, from 10 wppb to 15 wppm, from 10 wppb to 12wppm, from 10 wppb to 10 wppm, from 10 wppb to 5 wppm, from 100 wppb to15 wppm, from 100 wppb to 10 wppm, or from 100 wppb to 5 wppm.

The finished acesulfame potassium compositions, which are typicallysuitable for end consumer usage, are formed by treating the crudeacesulfame potassium composition to remove impurities, as discussedherein. This finished acesulfame potassium composition preferablycomprises non-chlorinated acesulfame potassium, e.g., non-chlorinatedacesulfame potassium, and less than 39 wppm 5-chloro-acesulfamepotassium, e.g., less than 35 wppm, less than 34 wppm, less than 33wppm, less than 32 wppm, less than 31 wppm, less than 30 wppm, less than25 wppm, less than 24 wppm, less than 20 wppm, less than 15 wppm, lessthan 12 wppm, less than 10 wppm, less than 7 wppm, less than 5 wppm,less than 3 wppm, or less than 1 wppm. In some cases the finishedacesulfame potassium composition is free of 5-chloro-acesulfamepotassium, e.g., substantially free of 5-chloro-acesulfame potassium(undetectable). In terms of ranges, the finished acesulfame potassiumcomposition may comprise from 1 wppb to 39 wppm 5-chloro-acesulfamepotassium, e.g., from 1 wppb to 35 wppm, from 1 wppb to 34 wppm, from 1wppb to 33 wppm, from 1 wppb to 32 wppm, from 1 wppb to 31 wppm, from 1wppb to 30 wppm, from 50 wppb to 34 wppm, from 0.1 wppm to 34 wppm, from0.1 wppb to 34 wppm, from 0.1 wppb to 33 wppm, from 1 wppb to 25 wppm,from 1 wppb to 20 wppm, from 1 wppb to 10 wppm, from 1 wppb to 5 wppm,from 1 wppb to 2.7 wppm, from 10 wppb to 20 wppm, from 10 wppb to 19wppm, from 10 wppb to 15 wppm, from 10 wppb to 12 wppm, from 10 wppb to10 wppm, from 10 wppb to 5 wppm, from 100 wppb to 15 wppm, from 100 wppbto 10 wppm, or from 100 wppb to 5 wppm. The lower temperatures of thecyclizing agent composition (and optionally the shorter contact times)reduce or eliminate 5-chloro-acesulfame potassium formation, resultingin both a crude acesulfame potassium composition and a finishedacesulfame potassium composition having low 5-chloro-acesulfamepotassium content.

In some embodiments, the finished acesulfame potassium compositionscomprise acesulfame potassium and less than 33 wppm acetoacetamide,e.g., less than 32 wppm, less than 30 wppm, less than 25 wppm, less than20 wppm, less than 15 wppm, less than 12 wppm, less than 10 wppm, lessthan 7 wppm, less than 5 wppm, less than 3 wppm, less than 1 wppm, lessthan 0.8 wppm, less than 0.5 wppm, or less than 0.3 wppm. In some casesthe finished acesulfame potassium composition is free of acetoacetamide,e.g., substantially free of acetoacetamide (undetectable). In terms ofranges, the finished acesulfame potassium composition may comprise from1 wppb to 33 wppm acetoacetamide, e.g., from 10 wppb to 32 wppm, from 10wppb to 25 wppm, from 10 wppb to 15 wppm, from 10 wppb to 12 wppm, from10 wppb to 10 wppm, from 10 wppb to 7 wppm, from 10 wppb to 5 wppm, from10 wppb to 3 wppm, from 100 wppb to 15 wppm, from 100 wppb to 10 wppm,or from 100 wppb to 5 wppm. In some cases, acetoacetamide-N-sulfonicacid may also be present in the finished acesulfame potassiumcompositions in the aforementioned amounts. These impurities may beformed by side reactions and degradation of the acesulfame potassium andacesulfame-H molecules, e.g., during treatment of the specific crudeacesulfame potassium compositions discussed herein.

The 5-chloro-acesulfame potassium content may be measured in the crudeand/or finished acesulfame potassium compositions (as well as anyintermediate compositions) via high performance liquid chromatography(HPLC) analysis, based on European Pharmacopoeia guidelines (2017),based on European Pharmacopoeia guidelines for thin layer chromatography(2017) and adapted for HPLC. A particular measurement scenario utilizesan LC Systems HPLC unit from Shimadzu having a CBM-20 Shimadzucontroller and being equipped with a CC 250/4.6 Nucleodur 100-3 C18 ec(250×4.6 mm) MACHEREY NAGEL column. A Shimadzu SPD-M20A photodiode arraydetector can be used for detection (at 234 nm wavelength). Analysis maybe performed at 23° C. column temperature. As an eluent solution, anaqueous solution of tetra butyl ammonium hydrogen sulfate (optionally at3.4 g/L and at 60% of the total solution) and acetonitrile (optionallyat 300 mL/L and at 40% of the total solution) may be employed. Elutionmay be isocratic. The overall flow rate of total eluent may beapproximately 1 mL/min. The data collection and calculations may beperformed using Lab Solution software from Shimadzu.

The acetoacetamide-N-sulfonic acid and/or the acetoacetamide content maybe measured in the crude, intermediate, or finished acesulfame potassiumcompositions via HPLC analysis, based on European Pharmacopoeiaguidelines for thin layer chromatography (2017) and adapted for HPLC. Aparticular measurement scenario utilizes an LC Systems HPLC unit fromShimadzu having a CBM-20 Shimadzu controller and being equipped with anIonPac NS1 ((5 μm) 150×4 mm) analytical column and an IonPac NG1 guardcolumn (35×4.0 mm). A Shimadzu SPD-M20A photodiode array detector can beused for detection (at 270 nm and 280 nm wavelength). Analysis may beperformed at 23° C. column temperature. As a first eluent solution, anaqueous mixture of tetra butyl ammonium hydrogen sulfate (3.4 g/L),acetonitrile (300 mL/L), and potassium hydroxide (0.89 g/L) may beemployed; as a second eluent solution, an aqueous mixture of tetra butylammonium hydrogen sulfate (3.4 g/L) and potassium hydroxide (0.89 g/L)may be employed. Elution may be conducted in gradient mode according tothe following second eluent flow profile:

-   -   0 to 3 minutes: constant 80% (v/v)    -   3 to 6 minutes: linear reduction to 50% (v/v)    -   6 to 15 minutes: constant at 50% (v/v)    -   15 to 18 minutes: linear reduction to 0%    -   18 to 22 minutes: constant at 0%    -   22 to 24 minutes: linear increase to 80% (v/v)    -   24 to 35 minutes constant at 80% (v/v).        Overall flow rate of eluent may be approximately 1.2 mL/min. The        data collection and calculations may be performed using Lab        Solution software from Shimadzu.

As noted above, the crude acesulfame potassium composition is formed bythe aforementioned cooling of the cyclizing agent composition/provisionof a cooled cyclizing agent composition, cyclic sulfur trioxide adductcomposition formation reaction, hydrolysis, and neutralization steps andthe finished acesulfame potassium composition is formed by treatment ofthe crude acesulfame potassium composition. In preferred embodiments,the cooled cyclizing agent composition may have a temperature less than35° C., e.g., e.g., less than 32° C., less than 30° C., less than 25°C., less than 20° C., less than 15° C., less than 12° C., less than 11°C., less than 10° C., less than 8° C., less than 5° C., less than 3° C.,less than 1° C., or less than 0° C. (optionally a temperature rangingfrom −45° C. to 35° C., e.g., −45° C. to 25° C., −40° C. to 15° C., −35°C. to 15° C.,−35° C. to 10° C., −30° C. to 25° C., −30° C. to 10° C.,−15° C. to 25° C., from −15° C. to 15° C., from −10° C. to 12° C., from−8° C. to 10° C., or −8° C. to 5° C.); the contact time may be less than60 minutes, e.g., less than 45 minutes, less than 30 minutes, less than15 minutes, less than 10 minutes, less than 8 minutes, less than 5minutes, less than 3 minutes, or less than 1 minute (optionally rangingfrom 1 second to 60 minutes, e.g., from 1 second to 45 minutes, from 1second to 30 minutes, from 1 second to 15 minutes, from 1 second to 10minutes, from 1 minute to 45 minutes, from 1 minute to 30 minutes, from1 minute to 15 minutes, from 1 minute to 10 minutes, from 10 seconds to45 minutes, from 10 seconds to 30 minutes, from 30 seconds to 30minutes, from 1 minute to 10 minutes, from 3 minutes to 10 minutes, orfrom 5 minutes to 10 minutes); the crude acesulfame potassiumcomposition may comprise from 1 wppb to 39 wppm 5-chloro-acesulfamepotassium, e.g., from 1 wppb to 35 wppm, from 1 wppb to 34 wppm, from 1wppb to 33 wppm, from 1 wppb to 32 wppm, from 1 wppb to 31 wppm, from 1wppb to 30 wppm, from 50 wppb to 34 wppm, from 0.1 wppm to 34 wppm, from0.1 wppb to 34 wppm, from 0.1 wppb to 33 wppm, from 1 wppb to 25 wppm,from 1 wppb to 20 wppm, from 1 wppb to 10 wppm, from 1 wppb to 5 wppm,from 1 wppb to 2.7 wppm, from 10 wppb to 20 wppm, from 10 wppb to 19wppm, from 10 wppb to 15 wppm, from 10 wppb to 12 wppm, from 10 wppb to10 wppm, from 10 wppb to 5 wppm, from 100 wppb to 15 wppm, from 100 wppbto 10 wppm, or from 100 wppb to 5 wppm (optionally less than 35 wppm,less than 34 wppm, less than 33 wppm, less than 32 wppm, less than 31wppm, less than 30 wppm, less than 25 wppm, less than 24 wppm, less than20 wppm, less than 15 wppm, less than 12 wppm, less than 10 wppm, lessthan 7 wppm, less than 5 wppm, less than 3 wppm, or less than 1 wppm);and the finished acesulfame potassium composition may comprise from 1wppb to 39 wppm 5-chloro-acesulfame potassium, e.g., from 1 wppb to 35wppm, from 1 wppb to 34 wppm, from 1 wppb to 33 wppm, from 1 wppb to 32wppm, from 1 wppb to 31 wppm, from 1 wppb to 30 wppm, from 50 wppb to 34wppm, from 0.1 wppm to 34 wppm, from 0.1 wppb to 34 wppm, from 0.1 wppbto 33 wppm, from 1 wppb to 25 wppm, from 1 wppb to 20 wppm, from 1 wppbto 10 wppm, from 1 wppb to 5 wppm, from 1 wppb to 2.7 wppm, from 10 wppbto 20 wppm, from 10 wppb to 19 wppm, from 10 wppb to 15 wppm, from 10wppb to 12 wppm, from 10 wppb to 10 wppm, from 10 wppb to 5 wppm, from100 wppb to 15 wppm, from 100 wppb to 10 wppm, or from 100 wppb to 5wppm (optionally less than 39 wppm 5-chloro-acesulfame potassium, e.g.,less than 35 wppm, less than 34 wppm, less than 33 wppm, less than 32wppm, less than 31 wppm, less than 30 wppm, less than 25 wppm, less than24 wppm, less than 20 wppm, less than 15 wppm, less than 12 wppm, lessthan 10 wppm, less than 7 wppm, less than 5 wppm, less than 3 wppm, orless than 1 wppm).

In a particular embodiment, the cooled cyclizing agent composition has acooled temperature less than 25° C., the crude acesulfame potassiumcomposition comprises from 1 wppb to 39 wppm 5-chloro-acesulfamepotassium, the finished acesulfame potassium composition comprises from1 wppb to 5 wppm 5-chloro-acesulfame potassium.

In another particular embodiment, the cooled cyclizing agent compositionhas a cooled temperature ranging from −35° C. to 15° C., the crudeacesulfame potassium composition comprises from 1 wppb to 5 wppm5-chloro-acesulfame potassium, the finished acesulfame potassiumcomposition comprises from 1 wppb to 2.7 wppm 5-chloro-acesulfamepotassium.

In another particular embodiment, the cooled cyclizing agent compositionhas a cooled temperature less than 25° C., the contact time is less than15 minutes, the crude acesulfame potassium composition comprises from 1wppb to 39 wppm 5-chloro-acesulfame potassium, and the finishedacesulfame potassium composition comprises from 1 wppb to 5 wppm5-chloro-acesulfame potassium.

In another particular embodiment, the cooled cyclizing agent compositionhas a cooled temperature ranging from −35° C. to 15° C., the contacttime is less than 5 minutes, the crude acesulfame potassium compositioncomprises from 1 wppb to 39 wppm 5-chloro-acesulfame potassium, and thefinished acesulfame potassium composition comprises from 1 wppb to 5wppm 5-chloro-acesulfame potassium.

In another particular embodiment, the cooled cyclizing agent compositionhas a cooled temperature less than 25° C., the contact time is less than5 minutes, the crude acesulfame potassium composition comprises from 1wppb to 39 wppm 5-chloro-acesulfame potassium, and the finishedacesulfame potassium composition comprises from 1 wppb to 5 wppm5-chloro-acesulfame potassium.

The acesulfame potassium compositions (crude and/or finished) may, insome cases, comprise other impurities. Exemplary impurities include,inter alia, acetoacetamide, acetoacetamidesulfonate, andacetoacetamide-N-sulfonic acid. The acesulfame potassium compositions(crude and/or finished) also may comprise heavy metals. The organicimpurities and/or heavy metals may be present in an amount ranging from1 wppb to 25 wppm, based on the total weight of the respectiveacesulfame potassium composition, crude or finished, e.g., from 100 wppbto 20 wppm, from 100 wppb to 15 wppm, from 500 wppb to 10 wppm, or from1 wppm to 5 wppm. Heavy metals are defined as metals with relativelyhigh densities, e.g., greater than 3 g/cm³ or greater than 7 g/cm³.Exemplary heavy metals include lead and mercury. In some cases, thecrude or finished acesulfame potassium composition may comprise mercuryin an amount ranging from 1 wppb to 25 wppm, e.g., from 100 wppb to 20wppm, from 100 wppb to 15 wppm, from 500 wppb to 10 wppm, or from 1 wppmto 5 wppm. In terms of limits, the crude or finished acesulfamepotassium composition may comprise less than 25 wppm mercury, e.g., lessthan 20 wppm, less than 15 wppm, less than 10 wppm, or less than 5 wppm.In some cases, the crude or finished acesulfame potassium compositionmay comprise lead in an amount ranging from 1 wppb to 25 wppm, e.g.,from 100 wppb to 20 wppm, from 100 wppb to 15 wppm, from 500 wppb to 10wppm, or from 1 wppm to 5 wppm. In terms of limits, the crude orfinished acesulfame potassium composition may comprise less than 25 wppmlead, e.g., less than 20 wppm, less than 15 wppm, less than 10 wppm, orless than 5 wppm. In some cases, when potassium hydroxide is formed viaa membrane process, the resultant crude or finished acesulfame potassiumcomposition may have very low levels of mercury, if any, e.g., less than10 wppm, less than 5 wppm, less than 3 wppm, less than 1 wppm, less than500 wppb, or less than 100 wppb.

In some embodiments, the acesulfame potassium compositions (crude,intermediate, and/or finished) may comprise acetoacetamide-N-sulfonicacid, e.g., less than 37 wppm acetoacetamide-N-sulfonic acid, e.g., lessthan 35 wppm, less than 30 wppm, less than 25 wppm, less than 20 wppm,less than 15 wppm, less than 12 wppm, less than 10 wppm, less than 7wppm, less than 5 wppm, less than 3 wppm, less than 1 wppm, less than0.8 wppm, less than 0.5 wppm, or less than 0.3 wppm. In some cases thefinished acesulfame potassium composition is substantially free ofacetoacetamide-N-sulfonic acid, e.g., free of acetoacetamide-N-sulfonicacid. In terms of ranges, the finished acesulfame potassium compositionmay comprise from 1 wppb to 37 wppm acetoacetamide-N-sulfonic acid,e.g., from 10 wppb to 35 wppm, from 10 wppb to 25 wppm, from 10 wppb to15 wppm, from 10 wppb to 12 wppm, from 10 wppb to 10 wppm, from 10 wppbto 7 wppm, from 10 wppb to 5 wppm, from 10 wppb to 3 wppm, from 100 wppbto 15 wppm, from 100 wppb to 10 wppm, or from 100 wppb to 5 wppm.Acetoacetamide-N-sulfonic acid may be formed in side reactions. The useof the aforementioned temperature (and optionally contact time)parameters also provide for low amounts of acetoacetamide-N-sulfonicacid.

In some embodiments, the crude acesulfame potassium composition istreated to achieve the finished acesulfame potassium composition. Insome cases, however, treatment steps may not provide for removal of5-chloro-acesulfame potassium, perhaps due to the chemical similaritiesof 5-chloro-acesulfame potassium and acesulfame potassium. Surprisingly,the use of the process steps disclosed herein advantageously providesfor the reduction or elimination of impurities during the reactionscheme, before purification of the crude acesulfame potassiumcomposition. Accordingly, the need to rely on purification of the crudeacesulfame potassium composition to remove 5-chloro-acesulfame potassiumis beneficially reduced. In some embodiments, the acesulfame potassiumcompositions (crude and/or finished) comprise at least 90% of the5-chloro-acesulfame potassium present the crude acesulfame potassiumcomposition, e.g., at least 93%, at least 95%, or at least 99%.

Intermediate Reaction Parameters

The reactions for production of high purity acesulfame potassium aredescribed in more detail as follows.

Amidosulfamic Acid Salt Formation Reaction

In a first reaction step, sulfamic acid and an amine are reacted to formsulfamic acid salt. An exemplary reaction scheme that employstriethylamine as the amine and yields triethyl ammonium sulfamic acidsalt is shown in reaction (1), below.

H₂N—SO₃H+N(C₂H₅)₃→H₂N—SO₃ ⁻.HN⁺(C₂H₅)₃  (1)

Acetic acid is also present in the first reaction mixture and reactswith the amine, e.g., triethylamine, to form an ammonium acetate, e.g.,triethylammonium acetate, as shown in reaction (2), below.

H₃C—COOH+N(C₂H₅)₃→H₃C—COO⁻.HN⁺(C₂H₅)₃  (2)

The amine employed in these reactions may vary widely. Preferably, theamine comprises triethylamine. In one embodiment, the amine may beselected from the group consisting of trimethylamine,diethylpropylamine, tri-n-propylamine, triisopropylamine,ethyldiisopropylamine, tri-n-butylamine, triisobutylamine,tricyclohexylamine, ethyldicyclohexylamine, N,N-dimethylaniline,N,N-diethylaniline, benzyldimethylamine, pyridine, substituted pyridinessuch as picoline, lutidine, cholidine or methylethylpyridine,N-methylpiperidine, N-ethylpiperidine, N-methylmorpholine,N,N-dimethylpiperazine, 1,5-diazabicyclo[4.3.0]-non-5-en,1,8-diazabicyclo-[5.4.0]-undec-7-en, 1,4-diazabicyclooctane,tetramethylhexamethylendiamine, tetramethylethylendiamine,tetramethylpropylendiamine, tetramethylbutylendiamine,1,2-dimorpholylethan, pentamethyldiethyltriamine,pentaethyldiethylentriamine, pentamethyldipropylentriamine,tetramethyldiaminomethane, tetrapropyldiaminomethane,hexamethyltriethylentetramine, hexamethyltripropylenetetramine,diisobutylentriamine, triisopropylentriamine, and mixtures thereof.

Acetoacetamide Salt Formation Reaction

Once formed in reaction (1), the sulfamic acid salt is reacted with theacetoacetylating agent to form the acetoacetamide salt, preferablyacetoacetamide-N-sulfonate triethylammonium salt. Preferably, theacetoacetylating agent comprises diketene, although otheracetoacetylating agents may be employed, either with or withoutdiketene.

In one embodiment, the resultant acetoacetamide salt corresponds to thefollowing formula (3).

wherein M⁺ is an appropriate ion. Preferably, M⁺ is an alkali metal ionor N⁺R₁R₂R₃R₄. R₁, R₂, R₃ and R₄, independently of one another, may beorganic radicals or hydrogen, preferably H or C₁-C₈ alkyl, C₆-C₁₀cycloalkyl, aryl and/or aralkyl. In a preferred embodiment, R₁ ishydrogen, and R₂, R₃ and R₄ are alkyl, e.g., ethyl.

An exemplary reaction scheme for forming an acetoacetamide salt employsa trialkyl ammonium amidosulfamic acid salt and diketene as reactantsand yields an acetoacetamide triethylammonium salt is shown in reaction(4), below.

In one embodiment, the reaction is conducted in the presence of acatalyst, which may vary widely. In some embodiments, the catalystcomprises one or more amines and/or phosphines. Preferably, the catalystcomprises triethylamine. In some cases trimethylamine serves as both acatalyst and a reactant.

In one embodiment wherein the amidosulfamic acid salt formation reactionand the acetoacetamide salt formation reaction are conducted in separatereactors, a second reaction mixture comprises the amidosulfamic acidsalt, the diketene, and the catalyst, e.g., triethylamine. Preferably,catalyst from the first reaction is carried through to the reactionmixture of the second reaction. The second reaction mixture is thensubjected to conditions effective to form the acetoacetamide salt.

In one embodiment, the composition of the second reaction mixture may besimilar to that of the first reaction mixture. In a preferredembodiment, the reaction product of the amidosulfamic acid saltformation reaction provides the amidosulfamic acid salt component of thesecond reaction mixture. In addition to the above-mentioned components,the second reaction mixture may further comprise reaction by-productsfrom the first reaction or non-reacted starting materials.

In one embodiment, the amount of acetoacetylating agent, e.g., diketene,should be at least equimolar to the reactant amidosulfamic acid saltthat is provided. In one embodiment, the process may utilize a diketenein excess, but preferably in an excess less than 30 mol %, e.g., lessthan 10 mol %. Greater excesses are also contemplated.

The amidosulfamic acid salt formation reaction and/or the acetoacetamidesalt formation reaction may employ an organic solvent. Suitable inertorganic solvents include anyorganic solvents that do not react in anundesired manner with the starting materials, cyclizing agent, finalproducts and/or the catalysts in the reaction. The solvents preferablyhave the ability to dissolve, at least partially, amidosulfamic acidsalts. Exemplary organic solvents include halogenated aliphatichydrocarbons, preferably having up to 4 carbon atoms such as, forexample, methylene chloride, chloroform, 1,2-dichlorethane,trichloroethylene, tetrachloroethylene, trichlorofluoroethylene;aliphatic ketones, preferably those having 3 to 6 carbon atoms such as,for example, acetone, methyl ethyl ketone; aliphatic ethers, preferablycyclic aliphatic ethers having 4 or 5 carbon atoms such as, for example,tetrahydrofuran, dioxane; lower aliphatic carboxylic acids, preferablythose having 2 to 6 carbon atoms such as, for example, acetic acid,propionic acid; aliphatic nitriles, preferably acetonitrile;N-alkyl-substituted amides of carbonic acid and lower aliphaticcarboxylic acids, preferably amides having up to 5 carbon atoms such as,for example, tetramethylurea, dimethylformamide, dimethylacetamide,N-methylpyrrolidone; aliphatic sulfoxides, preferably dimethylsulfoxide, and aliphatic sulfones, preferably sulfolane.

Particularly preferred solvents include dichloromethane (methylenechloride), 1,2-dichloroethane, acetone, glacial acetic acid anddimethylformamide, with dichloromethane (methylene chloride) beingparticularly preferred. The solvents may be used either alone or in amixture. In one embodiment, the solvent is a halogenated, aliphatichydrocarbon solvent, preferably the solvent is dichloromethane.Chloroform and tetrachloromethane are also exemplary solvents.

In one embodiment, the acetoacetamide salt formation reaction isconducted a temperature ranging from −30° C. to 50° C., e.g., from 0° C.to 25° C. The reaction pressure may vary widely. In preferredembodiments, the reaction is carried out at atmospheric pressure,although other pressures are also contemplated. The reaction time mayvary widely, preferably ranging from 0.5 hours to 12 hours, e.g., from 1hour to 10 hours. In one embodiment, the reaction is carried out byintroducing the amidosulfamic acid salt and metering in the diketene. Inanother embodiment, the reaction is carried out by introducing diketeneand metering in the amidosulfamic acid salt. The reaction may be carriedout by introducing the diketene and amidosulfamic acid and metering inthe catalyst.

Once formed, each reaction product is optionally subjected to one ormore purification steps. For example, the solvent may be separated fromthe reaction product, e.g., via distillation, and the residue (mainlyacetoacetamide-N-sulfonate) may be recrystallized from a suitablesolvent such as, for example, acetone, methyl acetate or ethanol.

Generally speaking, the steps of reacting the sulfamic acid andtriethylamine to form an amidosulfamic acid salt, reacting theamidosulfamic acid salt and diketene to form acetoacetamide salt,providing the cyclizing agent composition, and cooling the cyclizingagent composition, may be performed in any order before the cyclizationreaction, e.g., the reaction of the acetoacetamide salt with sulfurtrioxide to form a cyclic sulfur trioxide adduct. Each of these stepsmay be performed independently of one another. In some cases, thesesteps may be performed in any order as long as they are performed beforethe cyclization reaction, e.g., the reaction of the acetoacetamide saltwith sulfur trioxide to form a cyclic sulfur trioxide adduct.

Cyclization and Hydrolyzation

As discussed above, the acetoacetamide salt is reacted with cyclizingagent, e.g., cyclizing agent in the cooled cyclizing agent composition,in the presence of a solvent to form the cyclic (sulfur trioxide) adductcomposition, which contains cyclic sulfur trioxide adduct and, in somecases, impurities. As discussed, a cooling step occurs before the cyclicsulfur trioxide adduct formation reaction. In one embodiment, thecyclization is achieved by using at least an equimolar amount of thecyclizing agent. The cyclizing agent may be dissolved in an inertinorganic or organic solvent. The cyclizing agent is generally used in amolar excess, e.g., up to a 20 fold excess, or up to a 10 fold excess,based on the total moles of acetoacetamide salt. An exemplarycyclization reaction using sulfur trioxide as the cyclizing agent isshown in reaction (5), below.

In one embodiment, the weight ratio of solvent to cyclizing agent in thecyclizing agent composition is at least 1:1, e.g., at least 2:1, or atleast 5:1. In one embodiment, the weight ratio of solvent to cyclizingagent in the cyclizing agent composition ranges from 1:1 to 25:1, e.g.,from 1:1 to 10:1, from 2:1 to 10:1, or from 5:1 to 10:1.

A cyclizing agent may be any compound that initiates the ring closure ofthe acetoacetamide salt. Although sulfur trioxide is a preferredcyclizing agent, the employment of other cyclizing agents iscontemplated.

Suitable inert inorganic or organic solvents are those liquids which donot react in an undesired manner with sulfur trioxide or the startingmaterials or final products of the reaction. Preferred organic solventsinclude, but are not limited to, halogenated aliphatic hydrocarbons,preferably having up to four carbon atoms, such as, for example,methylene chloride (dichloromethane), chloroform, 1,2-dichloroethane,trichloroethylene, tetrachloroethylene, trichlorofluoroethylene; estersof carbonic acid with lower aliphatic alcohols, preferably with methanolor ethanol; nitroalkanes, preferably having up to four carbon atoms, inparticular nitromethane; alkyl-substituted pyridines, preferablycollidine; and aliphatic sulfones, preferably sulfolane. Particularlypreferred solvents for the cyclization reaction include dichloromethane(methylene chloride), 1,2-dichloroethane, acetone, glacial acetic acidand dimethylformamide, with dichloromethane (methylene dichloride) beingparticularly preferred. Other solvents, e.g., other solvents mentionedherein, may also be suitable as solvents. The solvents may be usedeither alone or in a mixture. In one embodiment, the solvent is ahalogenated, aliphatic hydrocarbon solvent, preferably the solvent isdichloromethane. The processes may employ these solvents alone or inmixtures thereof.

In some cases, the solvent in the cyclizing agent composition may beselected from 1) concentrated sulfuric acid, 2) liquid sulfur dioxide,or 3) an inert organic solvent.

In a preferred embodiment, the same solvent is used in both theacetoacetamide salt formation reaction and the cyclization reaction. Asone benefit, the solution obtained in the acetoacetamide salt formationreaction, without isolation of the acetoacetamide salt formationreaction product, may be used immediately in the cyclization.

The pressure at which the reaction is conducted may vary widely. In oneembodiment, the reaction is conducted at a pressure ranging from 0.01MPa to 10 MPa, e.g., from 0.1 MPa to 5 MPa. Preferably, the reaction isconducted at atmospheric pressure.

The acetoacetamide salt may be introduced to the cyclization reactor andthe cooled cyclizing agent composition, e.g., a solution of cyclizingagent optionally in solvent, may be metered into the reactor. Inpreferred embodiments, both reactants (acetoacetamide salt and cyclizingagent) are simultaneously fed into the reactor. In one embodiment, thecooled cyclizing agent composition is initially introduced into thereactor and the acetoacetamide salt is added. Preferably, at least partof the cyclizing agent composition is introduced into the reactor and,either continuously or in portions, acetoacetamide salt and (additional)cyclizing agent are then metered in, preferably while maintaining thetemperature as described above.

The acetoacetamide salt may be introduced to the reactor and thecyclizing agent composition may be metered into the reactor. Inpreferred embodiments, both reactants are simultaneously fed into thereactor. In one embodiment, the cyclizing agent composition is initiallyintroduced into the reactor and the acetoacetamide salt is added.Preferably, at least part of the cyclizing agent composition isintroduced into the reactor and, either continuously or in portions,acetoacetamide salt and (additional) cyclizing agent are then meteredin, preferably while maintaining the temperature as described above.

The formation of the crude acesulfame potassium composition from thecyclic sulfur trioxide adduct composition, in some embodiments,comprises the steps of hydrolyzing the cyclic sulfur trioxide adduct toform an acesulfame-H composition; neutralizing the acesulfame-H in theacesulfame H composition to form a crude acesulfame potassiumcomposition; and forming the acesulfame potassium composition from thecrude acesulfame potassium composition.

The cyclic sulfur trioxide adduct may be hydrolyzed via conventionalmeans, e.g., using water. Thus, the forming step may comprise the stepsof hydrolyzing the cyclic sulfur trioxide adduct to form an acesulfame-Hcomposition. Acesulfame-H is referred to as sweetener acid.

An exemplary hydrolysis reaction scheme is shown in reaction (6), below.

The addition of the water leads to a phase separation. The majority ofthe sweetener acid, acesulfame-H(6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide), which isformed via the hydrolysis, is present in the organic phase, e.g., atleast 60 wt %, at least 70%, at least 80%, or at least 90%. Theremainder of the sweetener acid is in the water phase and can beextracted and optionally added to the sweetener acid in the organicphase. In cases where dichloromethane is used as the reaction medium,water or ice may be added, e.g., in a molar excess, based on the sulfurtrioxide, to the cyclic sulfur trioxide adduct/sulfur trioxide solution.

In some cases, the hydrolysis step comprises adding water to the cyclicsulfur trioxide adduct. In preferred embodiments, the weight ratio ofwater to acetoacetamide salt is greater than 1.3:1, e.g., greater than1.5:1, greater than 1.7:1, greater than 2:1 or greater than 2.2:1.Employment of these ratios may lead to decreases inacetoacetamide-N-sulfonic acid and/or acetoacetamide formation in theneutralized crude acesulfame potassium composition, e.g., the crudeacesulfame potassium composition may comprise acetoacetamide-N-sulfonicacid in the amounts discussed herein.

It was surprisingly discovered that the temperature at which the wateris initially fed to the hydrolysis reaction may have beneficial effectson impurity production, e.g., organic production or 5-chloro-acesulfamepotassium production as well as reaction parameters, e.g., temperature.At lower temperatures, e.g., lower than approximately −35° C. or lowerthan −22° C., ice tends to build up in the reaction mixture. As this icemelted, it led to the onset of additional reaction, which caused thetemperature to rise quickly. This rise in temperature surprisingly ledto a product that contained much higher levels of impurities. In somecases, the hydrolyzing comprises adding hydrolysis water to the cyclicsulfur trioxide adduct to form a hydrolysis reaction mixture andreacting the mixture to from the acesulfame-H composition. In someembodiments, the temperature of the hydrolysis reaction mixture or thetemperature at which the hydrolysis water is fed to the reactor ismaintained at a temperature greater than −35° C., e.g., greater than−30° C., greater than −25° C., greater than −24° C., greater than −23°C., greater than −22° C., greater than −21.5° C., greater than −21° C.,or greater than greater than −20° C. In terms of ranges, the temperatureof the hydrolysis reaction mixture or the temperature at which thehydrolysis water is fed to the reactor optionally is maintained at atemperature ranging from −35° C. to 0° C., e.g., from −30° C. to −5° C.,from −20° C. to −5° C., from −30° C. to −20° C., from −25° C. to −21°C., or −25° C. to −21.5° C.

After the addition of water, the reaction solvent, e.g.,dichloromethane, may be removed by distillation, or the acesulfame-Hthat remains in the organic phase may be extracted with a more suitablesolvent. Suitable solvents are those which are sufficiently stabletowards sulfuric acid and which have a satisfactory dissolving capacity.Other suitable solvents include esters of carbonic acid such as, forexample dimethyl carbonate, diethyl carbonate and ethylene carbonate, oresters of organic monocarboxylic acids such as, for example, isopropylformate and isobutyl formate, ethyl acetate, isopropyl acetate, butylacetate, isobutyl acetate and neopentyl acetate, or esters ofdicarboxylic acids or amides which are immiscible with water, such as,for example, tetrabutylurea, are suitable. Isopropyl acetate andisobutyl acetate are particularly preferred.

The combined organic phases are dried with, for example, Na₂SO₄, and areevaporated. Any sulfuric acid which has been carried over in theextraction may be removed by appropriate addition of aqueous alkali tothe organic phase. For this purpose, dilute aqueous alkali may be addedto the organic phase until the pH reached in the aqueous phasecorresponds to that of pure 6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one2,2-dioxide at the same concentration in the same two-phase system ofextracting agent and water.

Neutralization

The neutralization of the acesulfame-H yields a non-toxic salt ofacesulfame-H, e.g., acesulfame potassium. In one embodiment,neutralization is carried out by reacting the acesulfame-H with anappropriate base, e.g., potassium hydroxide, in particular amembrane-produced potassium hydroxide. Other suitable bases include, forexample, KOH, KHCO₃, K₂CO₃, and potassium alcoholates. An exemplaryreaction scheme using potassium hydroxide as a neutralizing agent isshown in reaction (7), below.

In some cases, the neutralization is conducted or maintained at a low pHlevels, which may advantageously further result in a reduction orelimination of the formation of impurities, e.g., acetoacetamide salts.In this context, “conducted” means that the neutralization step beginsat a low pH level, and “maintained” means that steps are taken to ensurethat the pH stays within a low pH range throughout the entireneutralization step. In one embodiment, the neutralization step isconducted or maintained at a pH below 10.0, e.g., below 9.5, below 9.0,below 8.5, below 8.0, below 7.5, below 7.0, or below 6.5. In terms ofranges, the neutralization step is preferably conducted or maintained ata pH between 6.0 and 10.0, e.g., between 6.5 and 9.5, between 7.0 and9.0, or between 7.5 and 8.5.

In some cases, the pH in the neutralizing step may be maintained withinthe desired range by managing the components of the neutralizationreaction mixture, which comprises acesulfame-H and neutralizing agent(and also solvent). For example, the composition of the neutralizationreaction mixture may include from 1 wt % to 95 wt % neutralizing agent,e.g., from 10 wt % to 85 wt % or from 25 wt % to 75 wt %, and from 1 wt% to 95 wt % acesulfame-H, e.g., from 10 wt % to 85 wt % or from 25 wt %to 75 wt %. These concentration ranges are based on the mixture ofneutralization agent and acesulfame-H (not including solvent).

In one embodiment, the acesulfame-H may be neutralized and extracteddirectly from the purified organic extraction phase using an aqueouspotassium base. The acesulfame potassium then precipitates out, whereappropriate after evaporation of the solution, in the crystalline form,and it can also be recrystallized for purification.

In one embodiment, the process is not a small-scale batch process or alaboratory-scale process. For example, the inventive process forproducing a finished acesulfame potassium composition may yield at least50 grams of finished acesulfame potassium composition per batch, e.g.,at least 100 grams per batch, at least 500 grams per batch, at least 1kilogram per batch, or at least 10 kilograms per batch. In terms ofrates, the inventive process may yield at least 50 grams of finishedacesulfame potassium composition per hour, e.g., at least 100 grams perhour, at least 500 grams per hour, at least 1 kilogram per hour, or atleast 10 kilograms per hour.

FIG. 1 shows an exemplary acesulfame potassium process 100 in accordancewith the process described herein. Process 100 comprises amidosulfamicacid salt formation reactor 102 and acetoacetamide salt formationreactor 104. Although FIG. 1 shows separate reactors for the twointermediate formation reactions, other configurations, e.g., a onereactor process, are within the contemplation of the present process.Sulfamic acid is fed to amidosulfamic acid salt formation reactor 102via sulfamic acid feed line 106. Amine(s), preferably triethylamine, arefed to amidosulfamic acid salt formation reactor 102 via amine feed line108. In addition to sulfamic acid and amine(s), acetic acid is also fedto amidosulfamic acid salt formation reactor 102 (via feed line 110).The resultant reaction mixture in amidosulfamic acid salt formationreactor 102 is as discussed above. In amidosulfamic acid salt formationreactor 102, the sulfamic acid and the amine (in the presence of theacetic acid) are reacted to yield a crude amidosulfamic acid saltcomposition, which exits reactor 102 via line 112. Although not shown, areaction solvent, e.g., dichloromethane may also be present in theamidosulfamic acid salt formation reactor 102.

The crude amidosulfamic acid salt composition in line 112 is directed toacetoacetamide salt formation reactor 104. Diketene is fed toacetoacetamide salt formation reactor 104 via feed line 114. Inacetoacetamide salt formation reactor 104, the amidosulfamic acid saltand the diketene are reacted to yield a crude acetoacetamide saltcomposition, which exits reactor 104 via line 118. Although not shown,dichloromethane may also be present in the acetoacetamide salt formationreactor 104.

Cyclizing agent (sulfur dioxide) and solvent (dichloromethane) are fedto vessel 119 via feed lines 121 and 123. Vessel 119 is preferably acooling vessel wherein the cyclizing agent composition (as discussedabove) is formed. The cyclizing agent composition exits vessel 119 vialine 125.

The crude acetoacetamide salt composition is directed to cyclizationreactor 120 via line 118. The cooled cyclizing agent composition is alsodirected to cyclization reactor 120 (via line 125). Line 125 ispreferably made of a material and in such a size and shape to facilitatethe residence times discussed herein. In cyclization reactor 120, theacetoacetamide salt in the crude acetoacetamide salt composition in line118 is cyclized and a cyclic sulfur trioxide adduct stream exits vialine 124.

The cyclic sulfur trioxide adduct in line 124, is directed to hydrolysisreactor 126. Water is fed to hydrolysis reactor 126 via water feed 128.In hydrolysis reactor 126, the cyclic sulfur trioxide adduct ishydrolyzed to yield a crude acesulfame-H composition, which exitshydrolysis reactor 126 via line 130 and is directed to phase separationunit 132. Phase separation unit 132 separates the contents of line 130into organic phase 134 and aqueous phase 136. Organic phase 134comprises a major amount of the acesulfame-H in line 130 as well assolvent, e.g., methylene chloride. Aqueous phase 136 exits via line 137and comprises triethylammonium sulfate, and optionally sulfuric acid andminor amounts of acesulfame-H. This aqueous phase may be furtherpurified to separate and/or recover the acesulfame-H and/or thetriethylammonium sulfate. The recovered acesulfame-H may be combinedwith the acesulfame from the organic phase (not shown).

Organic phase 134 exits phase separation unit 132 and is directed toextraction column 138 (via line 140). Water is fed to extraction column138 via water feed 142. The water extracts residual sulfates from thecontents of line 140 and a purified acesulfame-H composition exitsextraction column 138 via line 144. The extracted sulfates exitextraction column 138 via line 145.

The purified acesulfame-H composition in line 144 is directed toneutralization unit 146. Potassium hydroxide is also fed toneutralization unit 146 (via line 148). The potassium hydroxideneutralizes the acesulfame-H in the purified acesulfame-H composition toyield a product comprising acesulfame potassium, dichloromethane, water,potassium hydroxide, and impurities, e.g., 5-chloro-acesulfamepotassium, which exits neutralization unit 146 via line 150. Thisproduct may be considered a crude acesulfame potassium composition.

The product in line 150 is directed to phase separation unit 160. Phaseseparation unit 160 separates the product in line 150 into organic phase162 and an aqueous phase 164. Aqueous phase 164 comprises a major amountof the acesulfame potassium in line 150 as well as some impurities.Organic phase 162 comprises potassium hydroxide, dichloromethane, andwater and may be further treated to recover these components. Aqueousphase 164 (without any further treatment) may be considered a crudeacesulfame potassium composition. Aqueous phase 164 may be optionallytreated to form a finished acesulfame potassium composition.

Aqueous phase 164 is directed to treatment unit 156 via line 166. Intreatment unit 156, aqueous phase 164 is treated to obtain finishedacesulfame potassium composition (product that may be sold), which isshown exiting via stream 152. In addition to the finished acesulfamepotassium composition, dichloromethane and potassium hydroxide may beseparated. These components exit treatment unit 156 via line 154. Thecontents of stream 154 may be recovered and/or recycled to the process.

The crude acesulfame potassium product stream comprises acesulfamepotassium, dichloromethane, water, and potassium hydroxide. The crudeacesulfame potassium product stream in line 150 may be directed tofurther processing to recover purified acesulfame potassium, which isshown exiting via stream 152. In addition to the purified acesulfamepotassium, dichloromethane and potassium hydroxide may be separated fromthe crude acesulfame potassium product stream, as shown by stream 154.The contents of stream 154 may be recovered and/or recycled to theprocess.

The invention relates also to the following aspects:

Aspect 1: A process for producing a finished acesulfame potassiumcomposition, the process comprising the steps of:

-   -   (a) providing a cyclizing agent composition comprising a        cyclizing agent and a solvent and having an initial temperature;    -   (b) cooling the cyclizing agent composition to form a cooled        cyclizing agent composition having a cooled temperature less        than 35° C.;    -   (c) reacting an acetoacetamide salt with the cyclizing agent in        the cooled cyclizing agent composition to form a cyclic sulfur        trioxide adduct composition comprising cyclic sulfur trioxide        adduct; and    -   (d) forming the finished acesulfame potassium composition from        the cyclic sulfur trioxide adduct in the cyclic sulfur trioxide        adduct composition, wherein the finished acesulfame potassium        composition comprises non-chlorinated acesulfame potassium and        less than 39 wppm 5-chloro-acesulfame potassium;    -   wherein the cooled temperature is at least 2° C. less than the        initial temperature.

Aspect 2: The process of aspect 1, wherein the forming comprises:

-   -   hydrolyzing the cyclic sulfur trioxide adduct in the cyclic        sulfur trioxide adduct composition to form an acesulfame-H        composition; and    -   neutralizing the acesulfame-H in the acesulfame H composition to        form a crude acesulfame potassium composition comprising        non-chlorinated acesulfame potassium and less than 39 wppm        5-chloro-acesulfame potassium; and    -   forming the finished acesulfame potassium composition from the        crude acesulfame potassium composition.

Aspect 3: The process of any one of the preceding aspects, wherein theproviding step (a) comprises the step of contacting the solvent and thecyclizing agent to form the cyclizing agent composition; and wherein acontact time from the beginning of the contacting step to the beginningof reacting step (c) is less than 60 minutes.

Aspect 4: The process of any one of the preceding aspects, wherein thefinished acesulfame potassium composition comprises from 1 wppb to 5wppm 5-chloro-acesulfame potassium.

Aspect 5: The process of any one of the preceding aspects, wherein thecooled cyclizing agent composition has a cooled temperature less than25° C. and the crude acesulfame potassium composition comprises from 1wppb to 39 wppm 5-chloro-acesulfame potassium and the finishedacesulfame potassium composition comprises from 1 wppb to 5 wppm5-chloro-acesulfame potassium.

Aspect 6: The process of any one of the preceding aspects, wherein thecooled cyclizing agent composition has a cooled temperature ranging from−35° C. to 15° C. and the crude acesulfame potassium compositioncomprises from 1 wppb to 5 wppm 5-chloro-acesulfame potassium and thefinished acesulfame potassium composition comprises from 1 wppb to 2.7wppm 5-chloro-acesulfame potassium.

Aspect 7: The process of any one of the preceding aspects, wherein thecooled cyclizing agent composition has a cooled temperature less than25° C. and the contact time is less than 15 minutes and the crudeacesulfame potassium composition comprises from 1 wppb to 39 wppm5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.

Aspect 8: The process of any one of the preceding aspects, wherein thecooled cyclizing agent composition has a cooled temperature ranging from−35° C. to 15° C. and the contact time is less than 5 minutes and thecrude acesulfame potassium composition comprises from 1 wppb to 39 wppm5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.

Aspect 9: The process of any one of the preceding aspects, wherein thefinished acesulfame potassium composition comprises at least 90% byweight of the 5-chloro-acesulfame potassium present in the crudeacesulfame potassium composition.

Aspect 10: The process of any one of the preceding aspects, wherein thefinished acesulfame potassium composition comprises at least 90% byweight of the 5-chloro-acesulfame potassium present in the crudeacesulfame potassium composition.

Aspect 11: The process of any one of the preceding aspects, wherein theforming of the finished acesulfame potassium composition from the crudeacesulfame potassium composition comprises the steps of: concentratingthe crude acesulfame composition to form an intermediate acesulfamepotassium composition comprising at least 10 wt % acesulfame potassium;and separating the intermediate acesulfame potassium composition to formthe finished acesulfame potassium composition comprising at least 15 wt% acesulfame potassium.

Aspect 12: The process of any one of the preceding aspects, wherein thecooled cyclizing agent composition comprises less than 1 wt % cyclizingagent/solvent reaction product selected from the group consisting ofchloromethyl chlorosulfate and methyl-bis-chlorosulfate.

Aspect 13: The process of any one of the preceding aspects, wherein theweight ratio of solvent to cyclizing agent in the cyclizing agentcomposition is at least 1:1.

Aspect 14: A process for producing a finished acesulfame potassiumcomposition, the process comprising the steps of:

-   -   (a) cooling a solvent;    -   (b) combining the cooled solvent with a cyclizing agent to form        a cooled cyclizing agent composition having a cooled temperature        less than 35° C.;    -   (c) reacting an acetoacetamide salt with the cyclizing agent in        the cyclizing agent composition to form a cyclic sulfur trioxide        adduct composition comprising a sulfur trioxide adduct; and    -   (d) forming the finished acesulfame potassium composition from        the cyclic sulfur trioxide adduct composition, wherein the        finished acesulfame potassium composition comprises        non-chlorinated acesulfame potassium and less than 39 wppm        5-chloro acesulfame potassium.

Aspect 15: The process of aspect 14, wherein the finished acesulfamepotassium composition comprises from 1 wppb to 5 wppm chloro-acesulfamepotassium.

Aspect 16: A process for producing a finished acesulfame potassiumcomposition, the process comprising the steps of:

-   -   (a) providing a cyclic sulfur trioxide adduct composition        comprising one or more of chloromethyl chlorosulfate and        methyl-bis-chlorosulfate present in a collective amount less        than 1 wt %; and    -   (b) forming the finished acesulfame potassium composition from        the cyclic sulfur trioxide adduct composition, wherein the        finished acesulfame potassium composition comprises        non-chlorinated acesulfame potassium and less than 39 wppm        5-chloro-acesulfame potassium.

Aspect 17: The process of aspect 16, wherein the acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.

Aspect 18: The process of aspect 16 or 17, wherein the providing step(a) comprises

-   -   reacting sulfamic acid and triethylamine to form an        amidosulfamic acid salt;    -   reacting the amidosulfamic acid salt and diketene to form        acetoacetamide salt;    -   providing a cyclizing agent composition comprising a sulfur        trioxide and dichloromethane and having an initial temperature;    -   cooling the cyclizing agent composition to form a cooled        cyclizing agent composition having a cooled temperature below        35° C.;    -   reacting the acetoacetamide salt with sulfur trioxide in the        cooled cyclizing agent composition to form the cyclic sulfur        trioxide adduct composition;    -   wherein the cooled temperature is at least 2° C. less than the        initial temperature.

Aspect 19: The process of aspect 16-18, wherein the providing stepcomprises the step of contacting the solvent and the cyclizing agent toform the cyclizing agent composition and a contact time from thebeginning of the contacting step to the beginning of the reacting stepis less than 15 minutes, and wherein the cooled cyclizing agentcomposition has a cooled temperature less than 25° C. and the crudeacesulfame potassium composition comprises from 1 wppb to 39 wppm5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.

Aspect 20: The process of aspect 16-19, wherein the providing stepcomprises the step of contacting the solvent and the cyclizing agent toform the cyclizing agent composition and a contact time from thebeginning of the contacting step to the beginning of the reacting stepis less than 5 minutes, and wherein the cooled cyclizing agentcomposition has a cooled temperature ranging from −35° C. to 15° C. andthe crude acesulfame potassium composition comprises from 1 wppb to 39wppm 5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.

Aspect 21: A process for producing a finished acesulfame potassiumcomposition, the process comprising the steps of:

-   -   (a) reacting sulfamic acid and triethylamine to form an        amidosulfamic acid salt;    -   (b) reacting the amidosulfamic acid salt and diketene to form        acetoacetamide salt;    -   (c) providing a cyclizing agent composition comprising a sulfur        trioxide and dichloromethane and having an initial temperature;    -   (d) cooling the cyclizing agent composition to form a cooled        cyclizing agent composition having a cooled temperature less        than 35° C.;    -   (e) reacting the acetoacetamide salt with sulfur trioxide in the        cooled cyclizing agent composition to form a cyclic sulfur        trioxide adduct;    -   (f) hydrolyzing the cyclic sulfur trioxide adduct to form an        acesulfame-H composition comprising acesulfame-H;    -   (g) neutralizing the acesulfame-H in the acesulfame-H to form a        crude acesulfame potassium composition comprising        non-chlorinated acesulfame potassium and from 1 wppb to 39 wppm        5-chloro-acesulfame potassium acid,    -   (h) treating the crude acesulfame potassium composition to form        the finished acesulfame potassium composition comprising        acesulfame potassium and less than 37 wppm        acetoacetamide-N-sulfonic acid,        -   wherein steps (a), (b), (c), and (d) can be performed in any            order before the performance of step (e) and wherein the            cooled temperature is at least 2° C. less than the initial            temperature, and wherein the providing step (c) comprises            the step of contacting the solvent and the cyclizing agent            to form the cyclizing agent composition; and wherein a            contact time from the beginning of the contacting step to            the beginning of reacting step (e) is less than 60 minutes.

Aspect 22: The process of aspect 21, wherein contact time from thebeginning of the contacting step to the beginning of the reacting step(e) is less than 15 minutes, and wherein the cooled cyclizing agentcomposition has a cooled temperature less than 25° C. and the crudeacesulfame potassium composition comprises from 1 wppb to 39 wppm5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.

Aspect 23: The process of aspect 21 or 22, wherein contact time from thebeginning of the contacting step to the beginning of the reacting step(e) is less than 5 minutes, and wherein the cooled cyclizing agentcomposition has a cooled temperature ranging from −35° C. to 15° C. andthe crude acesulfame potassium composition comprises from 1 wppb to 39wppm 5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.

Aspect 24: A finished acesulfame potassium composition produced orproducible by, or obtainable or obtained from the process of any one ofaspects 1 to 23.

EXAMPLES Examples 1-3 and Comparative Example A

100 mmol of 99.5% pure sulfamic acid was suspended in 50 mLdichloromethane in a flask with reflux. Under continuous agitation, 105mmol of trimethylamine was added within approximately 3 minutes. Duringthis time, temperature increased due to acid/base exothermal reaction upto about 42° C. (the boiling point of dichloromethane). This firstreaction mixture was stirred for approximately 15 additional minutes,until no solid sedimentation was seen in the flask. Then, 10 mmol ofacetic acid was added to the first reaction mixture and was stirred forapproximately 15 additional minutes. At this point, within 7 minutes ofthe addition of the acetic acid, 110 mmol of diketene was added dropwiseto form a second reaction mixture. After the addition of all of thediketene was added to the second reaction mixture and approximately 15minutes of reaction time, this second reaction mixture was cooled. Theresultant cooled second reaction mixture contained approximately 30%acetoacetamide N-sulfonate triethylammonium salt. Additional batches ofcooled second reaction mixture were prepared as necessary. Theacetoacetamide N-sulfonate triethylammonium salt was used as discussedbelow.

Sulfur trioxide/dichloromethane compositions (cyclizing agentcompositions) were prepared by contacting approximately 15 wt % sulfurtrioxide and approximately 85 wt % dichloromethane with one another in aflask.

For Examples 1-3, the initial sulfur trioxide/dichloromethanecompositions were cooled from approximately 25° C. to lower temperaturesby placing the respective flask in a cooling bath containing a mixtureof isopropanol and dry ice before the cyclization reaction. For theComparative Example, the sulfur trioxide/dichloromethane composition waswarmed from approximately 25° C. to higher temperature by placing therespective flask in a warm water bath before the cyclization reaction.The cooled temperatures of the sulfur trioxide/dichloromethanecompositions for Examples 1-3 and the (warmed) temperature of the sulfurtrioxide/dichloromethane composition of Comparative Example A are shownin Table 1.

For Examples 1-3 and Comparative Example A, a reaction flask (a 4 neckedround bottom flask equipped with mechanical stirrer, thermometer, andfeed vessels) was placed into a cooling bath containing a mixture ofisopropanol and dry ice. Approximately 200 g of theacetoacetamide-N-sulfonate triethylammonium salt solution andapproximately 577 g of the sulfur trioxide/dichloromethane compositionswere measured.

The sulfur trioxide/dichloromethane compositions were held for varioustime periods before the start of the cyclization reaction. Approximately15 wt % of the total sulfur trioxide/dichloromethane composition(approximately 87 g) was initially fed to the reaction flask undercontinuous agitation by mechanical stirrer. When the temperature of thereaction flask contents reached −35° C. (due to the cooling batch), theremainder of the sulfur trioxide/dichloromethane composition and all ofthe acetoacetamide-N-sulfonate triethylammonium salt solution were fedinto the reaction flask. Contact times (the time periods that thesolvent contacted the cyclizing agent before formation of the cyclicsulfur trioxide adduct, e.g., before the acetoacetamide-N-sulfonatetriethylammonium salt solution was fed to the reaction flask) for therespective Examples 1-3 and Comparative Example A are shown in Table 1.The feed rate was controlled in such a way that the temperature of thereaction flask contents remained between −25° and −35° C. during thefeeding/cyclization reaction. After the reactants were fed, the reactionwas allowed to proceed for approximately one additional minute. Thecooling bath was then removed.

After approximately one minute, the temperature of the reaction flaskcontents reached approximately −22° C. At this time, hydrolysis wasinitiated by feeding deionized water to the reaction flask. Water wasfed over 10 minutes. The hydrolysis reaction was exothermic. Water wasadded slowly so as to maintain temperature between −20° C. and −5° C.After addition of water, reaction mixture was allowed to reach roomtemperature.

The hydrolyzed product was phase separated via a separating funnel. Aheavier organic sweetener acid-dichloromethane phase (acesulfame-Hcomposition) was separated out, and the remaining aqueous phase wasdiscarded.

The acesulfame-H in the acesulfame-H composition was neutralized with a10% potassium hydroxide solution. Neutralization was carried out at 25°C.±1° C. Potassium hydroxide addition was completed within 20 minutes.

After completion of the neutralization step, an additional phaseseparation was performed using a separating funnel to yield an aqueousphase containing acesulfame potassium (and some impurities) and anorganic phase. The aqueous phase is considered a crude acesulfamepotassium composition. The aqueous phase analyzed for impurities, e.g.,5-chloro acesulfame potassium. Testing for 5-chloro-acesulfame potassiumwas performed using the HPLC equipment and techniques discussed herein.In particular, the HPLC analysis was performed using an LC Systems HPLCunit from Shimadzu having a CBM-20 Shimadzu controller and beingequipped with a CC 250/4.6 Nucleodur 100-3 C18 ec (250×4.6 mm) MACHEREYNAGEL column. A Shimadzu SPD-M20A photodiode array detector was used fordetection (at 234 nm wavelength). Analysis was performed at 23° C.column temperature. As an eluent solution, an aqueous solution of tetrabutyl ammonium hydrogen sulfate (3.4 g/L and 60% of the total solution)and acetonitrile (HPLC grade) (300 mL/L and 40% of the total solution)was employed. Elution was isocratic. The overall flow rate of totaleluent was approximately 1 mL/min. The data collection and calculationswere performed using Lab Solution software from Shimadzu. The remainingdichloromethane phase was discarded. The results of the impurityanalysis for Examples 1-3 and Comparative Example A are shown in Table1.

Example 4

Liquid sulfur trioxide and dichloromethane were continuously fed,contacted to form a cyclizing agent composition, and cooled into astatic mixer at 1220 kg/h and 8000 kg/h, respectively. The temperatureof the cooled cyclizing agent composition was 11° C. The mixture washeld in the static mixture for less than 5 minutes and then fed into acyclization reactor, thus contact time was less than 5 minutes. In thecyclization reactor the cooled sulfur trioxide/dichloromethanecomposition was reacted with a solution of acetoacetamide-N-sulfonatetriethylammonium salt (acetoacetamide salt) in dichloromethane. Theresultant cyclized product was hydrolyzed and worked up to yield a crudeacesulfame potassium composition comprising (non-chlorinated) acesulfamepotassium. The crude acesulfame potassium was analyzed using the HPLCequipment and techniques discussed above. With a detection limit of 1wppm, no 5-chloro-acesulfame potassium was detected. The results of theimpurity analysis of Example 4 is also shown in Table 2.

TABLE 1 5-chloro Acesulfame Potassium Content in Crude AcesulfamePotassium Compositions Contact Cooled Time, Temperature, Temperature5-chloro Ace-K, Ex./Comp. Ex. min. ° C. Change, ° C. wppm Ex. 1 60  5°C. −20° C. 32 Ex. 2 30  5° C. −20° C. 23 Ex. 3 30 22° C.  −3° C. 33 Ex.4 <5 11° C. — Not detectable Comp. Ex. A 60 35° C.  +10° C. 39

As shown in the Examples, 5-chloro-acesulfame potassium content wasaffected by the cooling of the sulfur trioxide/dichloromethanecompositions prior to reaction to form the cyclic sulfur trioxideadduct. When the initial temperature of the sulfurtrioxide/dichloromethane compositions was cooled to a cooler temperatureby 2° C. or more, 5-chloro-acesulfame potassium content in the crudeacesulfame potassium composition was reduced. In contrast, when acooling step was not utilized (or when the sulfurtrioxide/dichloromethane composition was actually warmed),5-chloro-acesulfame potassium content in the crude acesulfame potassiumwas significantly greater (see Comparative Example A).

In addition, 5-chloro-acesulfame potassium content was affected bycontact time. In particular, when short contact times and larger coolingdifferentials were utilized, 5-chloro-acesulfame potassium content wassignificantly reduced (see Exs. 2 and 4).

Only minor and simple additional purifications of the crude acesulfamecomposition were necessary to form the finished acesulfame potassiumcompositions. Approximately 50% of water was evaporated out of the crudeacesulfame potassium compositions in roti vapor at reduced pressure. Theresultant concentrated acesulfame potassium composition was then cooledin a refrigerator at +5° C., which led to precipitation of “crudecrystals” containing mostly acesulfame potassium. The crude crystalswere then dissolved in enough water and this resultant solution washeated to 70° C. Activated carbon powder was then added to the solution.The solution (with the added activated carbon) was then filtered.

The filtrate that was yielded from the filtration was cooled to roomtemperature, which led to the formation of “intermediate crystals”containing mostly acesulfame potassium. The intermediate crystals weredissolved in sufficient water and heated to 70° C. in a water bath.

Activated carbon was added to this solution (of intermediate crystalsand activated carbon). This solution was then filtered. When filtratewas cooled down to room temperature, white-colored “pure crystals” ofacesulfame potassium were formed.

These pure crystals are considered the finished acesulfame potassiumcomposition. Testing for 5-chloro-acesulfame potassium was performedusing the HPLC equipment and techniques discussed above. The crystals ofthe finished acesulfame potassium composition contained the same amount(or slightly lower amounts) of 5-chloro-acesulfame potassium.

The purification steps did not show a marked reduction in5-chloro-acesulfame potassium content. It is believed that because thechemical structure of chloro-acesulfame potassium is similar to that ofacesulfame potassium, separation of chloro-acesulfame potassium usingstandard purification procedures such as crystallization is ineffective.This analysis demonstrates the importance of reducing/eliminating theproduction of 5-chloro-acesulfame potassium during the steps leading tothe formation of the crude acesulfame composition as described herein.

While the invention has been described in detail, modifications withinthe spirit and scope of the invention will be readily apparent to thoseof skill in the art. In view of the foregoing discussion, relevantknowledge in the art and references discussed above in connection withthe Background and Detailed Description, the disclosures of which areall incorporated herein by reference. In addition, it should beunderstood that aspects of the invention and portions of variousembodiments and various features recited above and/or in the appendedclaims may be combined or interchanged either in whole or in part. Inthe foregoing descriptions of the various embodiments, those embodimentswhich refer to another embodiment may be appropriately combined withother embodiments as will be appreciated by one of skill in the art.Furthermore, those of ordinary skill in the art will appreciate that theforegoing description is by way of example only, and is not intended tolimit the invention.

We claim:
 1. A process for producing a finished acesulfame potassiumcomposition, the process comprising the steps of: (a) providing acyclizing agent composition comprising a cyclizing agent and a solventand having an initial temperature; (b) cooling the cyclizing agentcomposition to form a cooled cyclizing agent composition having a cooledtemperature less than 35° C., wherein the cooled temperature is at least2° C. less than the initial temperature; (c) reacting an acetoacetamidesalt with the cyclizing agent in the cooled cyclizing agent compositionto form a cyclic sulfur trioxide adduct composition comprising cyclicsulfur trioxide adduct; and (d) forming the finished acesulfamepotassium composition from the cyclic sulfur trioxide adduct, whereinthe finished acesulfame composition comprises non-chlorinated acesulfamepotassium and less than 39 wppm 5-chloro-acesulfame potassium.
 2. Theprocess of claim 1, wherein the forming comprises: hydrolyzing thecyclic sulfur trioxide adduct in the cyclic sulfur trioxide adductcomposition to form an acesulfame-H composition; and neutralizing theacesulfame-H in the acesulfame-H composition to form a crude acesulfamepotassium composition comprising non-chlorinated acesulfame potassiumand less than 39 wppm 5-chloro-acesulfame potassium; and forming thefinished acesulfame potassium composition from the crude acesulfamepotassium composition.
 3. The process of claim 2, wherein the providingstep (a) comprises the step of contacting the solvent and the cyclizingagent to form the cyclizing agent composition; and wherein a contacttime from the beginning of the contacting step to the beginning ofreacting step (c) is less than 60 minutes.
 4. The process of claim 2,wherein the finished acesulfame potassium composition comprises from 1wppb to 5 wppm 5-chloro-acesulfame potassium.
 5. The process of claim 2,wherein the cooled cyclizing agent composition has a cooled temperatureless than 25° C. and the crude acesulfame potassium compositioncomprises from 1 wppb to 39 wppm 5-chloro-acesulfame potassium and thefinished acesulfame potassium composition comprises from 1 wppb to 5wppm 5-chloro-acesulfame potassium.
 6. The process of claim 2, whereinthe cooled cyclizing agent composition has a cooled temperature rangingfrom −35° C. to 15° C. and the crude acesulfame potassium compositioncomprises from 1 wppb to 5 wppm 5-chloro-acesulfame potassium and thefinished acesulfame potassium composition comprises from 1 wppb to 2.7wppm 5-chloro-acesulfame potassium.
 7. The process of claim 3, whereinthe cooled cyclizing agent composition has a cooled temperature lessthan 25° C. and the contact time is less than 15 minutes and the crudeacesulfame potassium composition comprises from 1 wppb to 39 wppm5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.
 8. The process of claim 3, wherein the cooled cyclizing agentcomposition has a cooled temperature ranging from −35° C. to 15° C. andthe contact time is less than 5 minutes and the crude acesulfamepotassium composition comprises from 1 wppb to 39 wppm5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.
 9. The process of claim 5, wherein the finished acesulfamepotassium composition comprises at least 90% by weight of the5-chloro-acesulfame potassium present in the crude acesulfame potassiumcomposition.
 10. The process of claim 7, wherein the finished acesulfamepotassium composition comprises at least 90% by weight of the5-chloro-acesulfame potassium present in the crude acesulfame potassiumcomposition.
 11. The process of claim 2, wherein the forming of thefinished acesulfame potassium composition from the crude acesulfamepotassium composition comprises the steps of: concentrating the crudeacesulfame composition to form an intermediate acesulfame potassiumcomposition comprising at least 10 wt % acesulfame potassium; andseparating the intermediate acesulfame potassium composition to form thefinished acesulfame potassium composition comprising at least 15 wt %acesulfame potassium.
 12. The process of claim 1, wherein the cooledcyclizing agent composition comprises less than 1 wt % cyclizingagent/solvent reaction product selected from the group consisting ofchloromethyl chlorosulfate and methyl-bis-chlorosulfate.
 13. The processof claim 1, wherein the weight ratio of solvent to cyclizing agent inthe cyclizing agent composition is at least 1:1.
 14. A process forproducing a finished acesulfame potassium composition, the processcomprising the steps of: (a) cooling a solvent; (b) combining the cooledsolvent with a cyclizing agent to form a cooled cyclizing agentcomposition having a cooled temperature less than 35° C.; (c) reactingan acetoacetamide salt with the cyclizing agent in the cyclizing agentcomposition to form a cyclic sulfur trioxide adduct compositioncomprising a sulfur trioxide adduct; and (d) forming the finishedacesulfame potassium composition from the cyclic sulfur trioxide adduct,wherein the finished acesulfame composition comprises non-chlorinatedacesulfame potassium and less than 39 wppm 5-chloro-acesulfamepotassium.
 15. The process of claim 14, wherein the finished acesulfamepotassium composition comprises from 1 wppb to 5 wppm chloro-acesulfamepotassium.
 16. A process for producing a finished acesulfame potassiumcomposition, the process comprising the steps of: (a) providing a cyclicsulfur trioxide adduct composition comprising one or more ofchloromethyl chlorosulfate and methyl-bis-chlorosulfate present in acollective amount less than 1 wt %; and (b) forming the finishedacesulfame potassium composition from the cyclic sulfur trioxide adductcomposition, wherein the finished acesulfame potassium compositioncomprises non-chlorinated acesulfame potassium and less than 39 wppm5-chloro-acesulfame potassium.
 17. The process of claim 16, wherein theacesulfame potassium composition comprises from 1 wppb to 5 wppm5-chloro-acesulfame potassium.
 18. The process of claim 16, wherein theproviding step (a) comprises reacting sulfamic acid and triethylamine toform an amidosulfamic acid salt; reacting the amidosulfamic acid saltand diketene to form acetoacetamide salt; providing a cyclizing agentcomposition comprising a sulfur trioxide and dichloromethane and havingan initial temperature; cooling the cyclizing agent composition to forma cooled cyclizing agent composition having a cooled temperature below35° C.; reacting the acetoacetamide salt with sulfur trioxide in thecooled cyclizing agent composition to form the cyclic sulfur trioxideadduct composition; wherein the cooled temperature is at least 2° C.less than the initial temperature.
 19. The process of claim 18, whereinthe providing step comprises the step of contacting the solvent and thecyclizing agent to form the cyclizing agent composition and a contacttime from the beginning of the contacting step to the beginning of thereacting step is less than 15 minutes, and wherein the cooled cyclizingagent composition has a cooled temperature less than 25° C. and thecrude acesulfame potassium composition comprises from 1 wppb to 39 wppm5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.
 20. The process of claim 18, wherein the providing stepcomprises the step of contacting the solvent and the cyclizing agent toform the cyclizing agent composition and a contact time from thebeginning of the contacting step to the beginning of the reacting stepis less than 5 minutes, and wherein the cooled cyclizing agentcomposition has a cooled temperature ranging from −35° C. to 15° C. andthe crude acesulfame potassium composition comprises from 1 wppb to 39wppm 5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.
 21. A process for producing a finished acesulfame potassiumcomposition, the process comprising the steps of: (a) reacting sulfamicacid and triethylamine to form an amidosulfamic acid salt; (b) reactingthe amidosulfamic acid salt and diketene to form acetoacetamide salt;(c) providing a cyclizing agent composition comprising a sulfur trioxideand dichloromethane and having an initial temperature; (d) cooling thecyclizing agent composition to form a cooled cyclizing agent compositionhaving a cooled temperature less than 35° C.; (e) reacting theacetoacetamide salt with sulfur trioxide in the cooled cyclizing agentcomposition to form a cyclic sulfur trioxide adduct; (f) hydrolyzing thecyclic sulfur trioxide adduct to form an acesulfame-H compositioncomprising acesulfame-H; (g) neutralizing the acesulfame-H in theacesulfame-H to form a crude acesulfame potassium composition comprisingnon-chlorinated acesulfame potassium and from 1 wppb to 39 wppm5-chloro-acesulfame potassium acid, (h) treating the crude acesulfamepotassium composition to form the finished acesulfame potassiumcomposition comprising acesulfame potassium and less than 37 wppmacetoacetamide-N-sulfonic acid, wherein steps (a), (b), (c), and (d) canbe performed in any order before the performance of step (e) and whereinthe cooled temperature is at least 2° C. less than the initialtemperature, and wherein the providing step (c) comprises the step ofcontacting the solvent and the cyclizing agent to form the cyclizingagent composition; and wherein a contact time from the beginning of thecontacting step to the beginning of reacting step (e) is less than 60minutes.
 22. The process of claim 21, wherein contact time from thebeginning of the contacting step to the beginning of the reacting step(e) is less than 15 minutes, and wherein the cooled cyclizing agentcomposition has a cooled temperature less than 25° C. and the crudeacesulfame potassium composition comprises from 1 wppb to 39 wppm5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.
 23. The process of claim 21, wherein contact time from thebeginning of the contacting step to the beginning of the reacting step(e) is less than 5 minutes, and wherein the cooled cyclizing agentcomposition has a cooled temperature ranging from −35° C. to 15° C. andthe crude acesulfame potassium composition comprises from 1 wppb to 39wppm 5-chloro-acesulfame potassium and the finished acesulfame potassiumcomposition comprises from 1 wppb to 5 wppm 5-chloro-acesulfamepotassium.
 24. A finished acesulfame potassium composition produced bythe process claim
 1. 25. A finished acesulfame potassium compositionproduced by the process claim
 14. 26. A finished acesulfame potassiumcomposition produced by the process claim
 16. 27. A finished acesulfamepotassium composition produced by the process claim 21.